cdn.undertone.com Open in urlscan Pro
2600:9000:2104:9600:1f:2473:9080:93a1  Public Scan

URL: https://cdn.undertone.com/js/usersync.html
Submission: On January 22 via api from DE

Summary

This website contacted 5 IPs in 5 countries across 8 domains to perform 8 HTTP transactions. The main IP is 2600:9000:2104:9600:1f:2473:9080:93a1, located in United States and belongs to AMAZON-02, US. The main domain is cdn.undertone.com.
TLS certificate: Issued by Amazon on December 11th 2020. Valid for: a year.
This is the only time cdn.undertone.com was scanned on urlscan.io!

urlscan.io Verdict: No classification

Domain & IP information

IP Address AS Autonomous System
1 2600:9000:210... 16509 (AMAZON-02)
1 1 23.37.42.132 16625 (AKAMAI-AS)
1 104.108.50.124 16625 (AKAMAI-AS)
1 185.33.221.91 29990 (ASN-APPNEX)
2 2 34.98.64.218 15169 (GOOGLE)
4 52.9.130.89 16509 (AMAZON-02)
2 2 18.197.99.6 16509 (AMAZON-02)
2 2 18.156.0.31 16509 (AMAZON-02)
2 2 54.171.98.69 16509 (AMAZON-02)
1 69.173.144.165 26667 (RUBICONPR...)
1 1 88.214.206.247 46636 (NATCOWEB)
8 5
Domain Requested by
4 usr.undertone.com cdn.undertone.com
2 match.adsrvr.org 2 redirects
2 ups.analytics.yahoo.com 2 redirects
2 pixel.advertising.com 2 redirects
2 us-u.openx.net 2 redirects
1 cs.admanmedia.com 1 redirects
1 pixel.rubiconproject.com cdn.undertone.com
1 ib.adnxs.com cdn.undertone.com
1 eus.rubiconproject.com cdn.undertone.com
1 secure-assets.rubiconproject.com 1 redirects
1 cdn.undertone.com
8 11

This site contains no links.

Subject Issuer Validity Valid
*.undertone.com
Amazon
2020-12-11 -
2022-01-09
a year crt.sh
*.rubiconproject.com
DigiCert TLS RSA SHA256 2020 CA1
2021-01-05 -
2022-01-18
a year crt.sh
*.adnxs.com
DigiCert ECC Secure Server CA
2019-01-23 -
2021-03-08
2 years crt.sh
*.ramp-ut.io
Amazon
2020-11-07 -
2021-12-06
a year crt.sh

This page contains 2 frames:

Primary Page: https://cdn.undertone.com/js/usersync.html
Frame ID: 29589EA25CF57D21EFF9B841664B2EB2
Requests: 7 HTTP requests in this frame

Frame: https://eus.rubiconproject.com/usync.html?p=12776
Frame ID: 33B464FE5264CDEEA2E092EB580E3100
Requests: 1 HTTP requests in this frame

Screenshot


Detected technologies

Overall confidence: 100%
Detected patterns
  • headers via /\(CloudFront\)$/i
  • headers server /^AmazonS3$/i

Overall confidence: 100%
Detected patterns
  • headers via /\(CloudFront\)$/i

Overall confidence: 100%
Detected patterns
  • headers server /^AmazonS3$/i

Page Statistics

8
Requests

100 %
HTTPS

9 %
IPv6

8
Domains

11
Subdomains

5
IPs

5
Countries

4 kB
Transfer

6 kB
Size

4
Cookies

Redirected requests

There were HTTP redirect chains for the following requests:

Request Chain 0
  • https://secure-assets.rubiconproject.com/utils/xapi/multi-sync.html?p=12776 HTTP 301
  • https://eus.rubiconproject.com/usync.html?p=12776
Request Chain 2
  • https://us-u.openx.net/w/1.0/cm?id=fba3d144-1026-4d31-a758-943b9545e305&r=https://usr.undertone.com/userPixel/sync?partnerId=39&uid= HTTP 302
  • https://us-u.openx.net/w/1.0/cm?cc=1&id=fba3d144-1026-4d31-a758-943b9545e305&r=https://usr.undertone.com/userPixel/sync?partnerId=39&uid= HTTP 302
  • https://usr.undertone.com/userPixel/sync?partnerId=39&uid=85a55794-5bf1-49ae-866a-9653cfa82ecc
Request Chain 3
  • https://pixel.advertising.com/ups/58293/sync?&gdpr=&gdpr_consent=&redir=true HTTP 302
  • https://pixel.advertising.com/ups/58293/sync?&gdpr=&gdpr_consent=&redir=true&verify=true HTTP 302
  • https://ups.analytics.yahoo.com/ups/58293/sync?&gdpr=&gdpr_consent=&redir=true&apid=UP7059cced-5c7e-11eb-a84c-024b77bec4b0 HTTP 302
  • https://ups.analytics.yahoo.com/ups/58293/sync?&gdpr=&gdpr_consent=&redir=true&apid=UP7059cced-5c7e-11eb-a84c-024b77bec4b0&verify=true HTTP 302
  • https://usr.undertone.com/userPixel/sync?partner=verizon&uid=y-Tcj1shF1l2Yc7Li2rDA8YCq5WGgYPAj7~UP7059cced-5c7e-11eb-a84c-024b77bec4b0
Request Chain 4
  • https://match.adsrvr.org/track/cmf/generic?ttd_pid=sirnsvg&ttd_tpi=1&gdpr=0&gdpr_consent= HTTP 302
  • https://match.adsrvr.org/track/cmb/generic?ttd_pid=sirnsvg&ttd_tpi=1&gdpr=0&gdpr_consent= HTTP 302
  • https://usr.undertone.com/userPixel/sync?partner=ttd&uid=391c9710-7b2f-4e51-bd78-a882ed33d242&ttl=1613890368
Request Chain 6
  • https://cs.admanmedia.com/sync/undertone?url=https%3A%2F%2Fusr.undertone.com%2FuserPixel%2Fsync%3Fpartner%3Dacuityads%26uid%3D%24UID HTTP 302
  • https://usr.undertone.com/userPixel/sync?partner=acuityads&uid=d9f569759e33fae8106328402f6bd9bd361fc422

8 HTTP transactions

Resource
Path
Size
x-fer
Type
MIME-Type
Primary Request usersync.html
cdn.undertone.com/js/
5 KB
2 KB
Document
General
Full URL
https://cdn.undertone.com/js/usersync.html
Protocol
H2
Security
TLS 1.3, , AES_128_GCM
Server
2600:9000:2104:9600:1f:2473:9080:93a1 , United States, ASN16509 (AMAZON-02, US),
Reverse DNS
Software
AmazonS3 /
Resource Hash
21d46bb0a238b8c1b0ab5ea12b5fa6cab58b90e30ca08727321e1e40e2970046

Request headers

:method
GET
:authority
cdn.undertone.com
:scheme
https
:path
/js/usersync.html
pragma
no-cache
cache-control
no-cache
upgrade-insecure-requests
1
user-agent
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36
accept
text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
sec-fetch-site
none
sec-fetch-mode
navigate
sec-fetch-user
?1
sec-fetch-dest
document
accept-encoding
gzip, deflate, br
accept-language
en-US
Upgrade-Insecure-Requests
1
User-Agent
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36

Response headers

content-type
text/html
last-modified
Wed, 16 Dec 2020 12:35:23 GMT
server
AmazonS3
content-encoding
gzip
date
Thu, 21 Jan 2021 21:56:39 GMT
etag
W/"8ee422394c26ec0371c4676b43dd838d"
vary
Accept-Encoding
x-cache
Hit from cloudfront
via
1.1 a156165ae278c5ddd408f18e7181dccd.cloudfront.net (CloudFront)
x-amz-cf-pop
AMS1-C1
x-amz-cf-id
Oxfta5i5wYNssCcT-ff9ptQfKdU-p7VYY7-AaMgO4ioPy7rzql36Fw==
age
32170
usync.html
eus.rubiconproject.com/ Frame 33B4
Redirect Chain
  • https://secure-assets.rubiconproject.com/utils/xapi/multi-sync.html?p=12776
  • https://eus.rubiconproject.com/usync.html?p=12776
0
0
Document
General
Full URL
https://eus.rubiconproject.com/usync.html?p=12776
Requested by
Host: cdn.undertone.com
URL: https://cdn.undertone.com/js/usersync.html
Protocol
HTTP/1.1
Security
TLS 1.3, , AES_256_GCM
Server
104.108.50.124 , Netherlands, ASN16625 (AKAMAI-AS, US),
Reverse DNS
a104-108-50-124.deploy.static.akamaitechnologies.com
Software
Apache/2.2.15 (CentOS) /
Resource Hash

Request headers

Host
eus.rubiconproject.com
Connection
keep-alive
Pragma
no-cache
Cache-Control
no-cache
Upgrade-Insecure-Requests
1
User-Agent
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36
Accept
text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Sec-Fetch-Site
cross-site
Sec-Fetch-Mode
navigate
Sec-Fetch-Dest
iframe
Referer
https://cdn.undertone.com/js/usersync.html
Accept-Encoding
gzip, deflate, br
Accept-Language
en-US
Upgrade-Insecure-Requests
1
User-Agent
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36
Referer
https://cdn.undertone.com/js/usersync.html

Response headers

Server
Apache/2.2.15 (CentOS)
Last-Modified
Mon, 28 Sep 2020 17:02:39 GMT
ETag
"4000c-123-5b062a240e9c0"
Accept-Ranges
bytes
Content-Encoding
gzip
Content-Length
238
Content-Type
text/html; charset=UTF-8
Date
Fri, 22 Jan 2021 06:52:48 GMT
Connection
keep-alive
Vary
Accept-Encoding

Redirect headers

Server
AkamaiGHost
Content-Length
0
Location
https://eus.rubiconproject.com/usync.html?p=12776
Date
Fri, 22 Jan 2021 06:52:48 GMT
Connection
keep-alive
Access-Control-Allow-Credentials
true
Access-Control-Allow-Origin
*
getuidnb
ib.adnxs.com/
43 B
693 B
Image
General
Full URL
https://ib.adnxs.com/getuidnb?https://usr.undertone.com/userPixel/sync?partner=appnexus&uid=$UID
Requested by
Host: cdn.undertone.com
URL: https://cdn.undertone.com/js/usersync.html
Protocol
HTTP/1.1
Security
TLS 1.2, ECDHE_ECDSA, AES_128_GCM
Server
185.33.221.91 , Netherlands, ASN29990 (ASN-APPNEX, US),
Reverse DNS
721.bm-nginx-loadbalancer.mgmt.ams1.adnexus.net
Software
nginx/1.17.9 /
Resource Hash
4b5b6b15c6255109e06720cce42a06d3aead8b7874423d9c52cb0303212c25ef
Security Headers
Name Value
X-Xss-Protection 0

Request headers

Referer
https://cdn.undertone.com/js/usersync.html
User-Agent
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36

Response headers

Pragma
no-cache
Date
Fri, 22 Jan 2021 06:52:48 GMT
X-Proxy-Origin
185.212.171.67; 185.212.171.67; 721.bm-nginx-loadbalancer.mgmt.ams1; *.adnxs.com; 185.33.223.146:80
AN-X-Request-Uuid
ed55db45-f2ef-41e8-8e5c-7ecb26779485
Server
nginx/1.17.9
P3P
policyref="http://cdn.adnxs.com/w3c/policy/p3p.xml", CP="NOI DSP COR ADM PSAo PSDo OURo SAMo UNRo OTRo BUS COM NAV DEM STA PRE"
Access-Control-Allow-Origin
*
Cache-Control
no-store, no-cache, private
Access-Control-Allow-Credentials
true
Connection
keep-alive
Content-Type
image/gif
Content-Length
43
X-XSS-Protection
0
Expires
Sat, 15 Nov 2008 16:00:00 GMT
sync
usr.undertone.com/userPixel/
Redirect Chain
  • https://us-u.openx.net/w/1.0/cm?id=fba3d144-1026-4d31-a758-943b9545e305&r=https://usr.undertone.com/userPixel/sync?partnerId=39&uid=
  • https://us-u.openx.net/w/1.0/cm?cc=1&id=fba3d144-1026-4d31-a758-943b9545e305&r=https://usr.undertone.com/userPixel/sync?partnerId=39&uid=
  • https://usr.undertone.com/userPixel/sync?partnerId=39&uid=85a55794-5bf1-49ae-866a-9653cfa82ecc
0
402 B
Image
General
Full URL
https://usr.undertone.com/userPixel/sync?partnerId=39&uid=85a55794-5bf1-49ae-866a-9653cfa82ecc
Requested by
Host: cdn.undertone.com
URL: https://cdn.undertone.com/js/usersync.html
Protocol
HTTP/1.1
Security
TLS 1.2, ECDHE_RSA, AES_128_GCM
Server
52.9.130.89 San Jose, United States, ASN16509 (AMAZON-02, US),
Reverse DNS
ec2-52-9-130-89.us-west-1.compute.amazonaws.com
Software
istio-envoy /
Resource Hash
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

Request headers

Referer
https://cdn.undertone.com/js/usersync.html
User-Agent
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36

Response headers

date
Fri, 22 Jan 2021 06:52:48 GMT
x-envoy-decorator-operation
tracking-service.ramplift-v2-p-us-west-1.svc.cluster.local:80/*
x-envoy-upstream-service-time
0
server
istio-envoy
Connection
keep-alive
Content-Length
0

Redirect headers

date
Fri, 22 Jan 2021 06:52:48 GMT
content-encoding
gzip
server
OXGW/16.200.0
vary
Accept, Accept-Encoding
p3p
CP="CUR ADM OUR NOR STA NID"
location
https://usr.undertone.com/userPixel/sync?partnerId=39&uid=85a55794-5bf1-49ae-866a-9653cfa82ecc
content-type
image/gif
alt-svc
clear
content-length
0
via
1.1 google
sync
usr.undertone.com/userPixel/
Redirect Chain
  • https://pixel.advertising.com/ups/58293/sync?&gdpr=&gdpr_consent=&redir=true
  • https://pixel.advertising.com/ups/58293/sync?&gdpr=&gdpr_consent=&redir=true&verify=true
  • https://ups.analytics.yahoo.com/ups/58293/sync?&gdpr=&gdpr_consent=&redir=true&apid=UP7059cced-5c7e-11eb-a84c-024b77bec4b0
  • https://ups.analytics.yahoo.com/ups/58293/sync?&gdpr=&gdpr_consent=&redir=true&apid=UP7059cced-5c7e-11eb-a84c-024b77bec4b0&verify=true
  • https://usr.undertone.com/userPixel/sync?partner=verizon&uid=y-Tcj1shF1l2Yc7Li2rDA8YCq5WGgYPAj7~UP7059cced-5c7e-11eb-a84c-024b77bec4b0
0
439 B
Image
General
Full URL
https://usr.undertone.com/userPixel/sync?partner=verizon&uid=y-Tcj1shF1l2Yc7Li2rDA8YCq5WGgYPAj7~UP7059cced-5c7e-11eb-a84c-024b77bec4b0
Requested by
Host: cdn.undertone.com
URL: https://cdn.undertone.com/js/usersync.html
Protocol
HTTP/1.1
Security
TLS 1.2, ECDHE_RSA, AES_128_GCM
Server
52.9.130.89 San Jose, United States, ASN16509 (AMAZON-02, US),
Reverse DNS
ec2-52-9-130-89.us-west-1.compute.amazonaws.com
Software
istio-envoy /
Resource Hash
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

Request headers

Referer
https://cdn.undertone.com/js/usersync.html
User-Agent
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36

Response headers

date
Fri, 22 Jan 2021 06:52:49 GMT
x-envoy-decorator-operation
tracking-service.ramplift-v2-p-us-west-1.svc.cluster.local:80/*
x-envoy-upstream-service-time
0
server
istio-envoy
Connection
keep-alive
Content-Length
0

Redirect headers

Date
Fri, 22 Jan 2021 06:52:48 GMT
Server
ATS/7.1.2.128
Age
0
Strict-Transport-Security
max-age=31536000
P3P
CP=NOI DSP COR LAW CURa DEVa TAIa PSAa PSDa OUR BUS UNI COM NAV
Location
https://usr.undertone.com/userPixel/sync?partner=verizon&uid=y-Tcj1shF1l2Yc7Li2rDA8YCq5WGgYPAj7~UP7059cced-5c7e-11eb-a84c-024b77bec4b0
Connection
keep-alive
Content-Length
0
sync
usr.undertone.com/userPixel/
Redirect Chain
  • https://match.adsrvr.org/track/cmf/generic?ttd_pid=sirnsvg&ttd_tpi=1&gdpr=0&gdpr_consent=
  • https://match.adsrvr.org/track/cmb/generic?ttd_pid=sirnsvg&ttd_tpi=1&gdpr=0&gdpr_consent=
  • https://usr.undertone.com/userPixel/sync?partner=ttd&uid=391c9710-7b2f-4e51-bd78-a882ed33d242&ttl=1613890368
0
402 B
Image
General
Full URL
https://usr.undertone.com/userPixel/sync?partner=ttd&uid=391c9710-7b2f-4e51-bd78-a882ed33d242&ttl=1613890368
Requested by
Host: cdn.undertone.com
URL: https://cdn.undertone.com/js/usersync.html
Protocol
HTTP/1.1
Security
TLS 1.2, ECDHE_RSA, AES_128_GCM
Server
52.9.130.89 San Jose, United States, ASN16509 (AMAZON-02, US),
Reverse DNS
ec2-52-9-130-89.us-west-1.compute.amazonaws.com
Software
istio-envoy /
Resource Hash
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

Request headers

Referer
https://cdn.undertone.com/js/usersync.html
User-Agent
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36

Response headers

date
Fri, 22 Jan 2021 06:52:48 GMT
x-envoy-decorator-operation
tracking-service.ramplift-v2-p-us-west-1.svc.cluster.local:80/*
x-envoy-upstream-service-time
0
server
istio-envoy
Connection
keep-alive
Content-Length
0

Redirect headers

pragma
no-cache
date
Fri, 22 Jan 2021 06:52:48 GMT
x-aspnet-version
4.0.30319
p3p
CP="NOI DSP COR CUR ADMo DEVo PSAo PSDo OUR SAMo BUS UNI NAV"
location
https://usr.undertone.com/userPixel/sync?partner=ttd&uid=391c9710-7b2f-4e51-bd78-a882ed33d242&ttl=1613890368
cache-control
private,no-cache, must-revalidate
content-type
text/html
content-length
247
sync.php
pixel.rubiconproject.com/exchange/
0
239 B
Image
General
Full URL
https://pixel.rubiconproject.com/exchange/sync.php?p=12776
Requested by
Host: cdn.undertone.com
URL: https://cdn.undertone.com/js/usersync.html
Protocol
HTTP/1.1
Security
TLS 1.2, RSA, AES_256_GCM
Server
69.173.144.165 Frankfurt am Main, Germany, ASN26667 (RUBICONPROJECT, US),
Reverse DNS
Software
/
Resource Hash
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

Request headers

Referer
https://cdn.undertone.com/js/usersync.html
User-Agent
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36

Response headers

Pragma
no-cache
Expires
0
Cache-Control
no-cache,no-store,must-revalidate
P3P
CP="NOI CURa ADMa DEVa TAIa OUR BUS IND UNI COM NAV INT"
X-RPHost
66ef90d06496cfd000aab8206f2b6221
Content-Type
image/gif
sync
usr.undertone.com/userPixel/
Redirect Chain
  • https://cs.admanmedia.com/sync/undertone?url=https%3A%2F%2Fusr.undertone.com%2FuserPixel%2Fsync%3Fpartner%3Dacuityads%26uid%3D%24UID
  • https://usr.undertone.com/userPixel/sync?partner=acuityads&uid=d9f569759e33fae8106328402f6bd9bd361fc422
0
406 B
Image
General
Full URL
https://usr.undertone.com/userPixel/sync?partner=acuityads&uid=d9f569759e33fae8106328402f6bd9bd361fc422
Requested by
Host: cdn.undertone.com
URL: https://cdn.undertone.com/js/usersync.html
Protocol
HTTP/1.1
Security
TLS 1.2, ECDHE_RSA, AES_128_GCM
Server
52.9.130.89 San Jose, United States, ASN16509 (AMAZON-02, US),
Reverse DNS
ec2-52-9-130-89.us-west-1.compute.amazonaws.com
Software
istio-envoy /
Resource Hash
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

Request headers

Referer
https://cdn.undertone.com/js/usersync.html
User-Agent
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.61 Safari/537.36

Response headers

date
Fri, 22 Jan 2021 06:52:48 GMT
x-envoy-decorator-operation
tracking-service.ramplift-v2-p-us-west-1.svc.cluster.local:80/*
x-envoy-upstream-service-time
0
server
istio-envoy
Connection
keep-alive
Content-Length
0

Redirect headers

Location
https://usr.undertone.com/userPixel/sync?partner=acuityads&uid=d9f569759e33fae8106328402f6bd9bd361fc422
Date
Fri, 22 Jan 2021 06:52:48 GMT
Server
nginx
Connection
keep-alive
Transfer-Encoding
chunked

Verdicts & Comments Add Verdict or Comment

21 JavaScript Global Variables

These are the non-standard "global" variables defined on the window object. These can be helpful in identifying possible client-side frameworks and code.

object| 0 object| ontransitionrun object| ontransitionstart object| ontransitioncancel object| cookieStore function| showDirectoryPicker function| showOpenFilePicker function| showSaveFilePicker object| trustedTypes boolean| crossOriginIsolated object| gdpr string| gdprStr object| path undefined| args undefined| keyval string| userIdEncCookie string| userIdCookie object| partners function| getCookie function| plantPixels function| getAllImgs

4 Cookies

Domain/Path Name / Value
.undertone.com/ Name: UID_EXT_50
Value: d9f569759e33fae8106328402f6bd9bd361fc422
.undertone.com/ Name: UID_EXT_46
Value: 391c9710-7b2f-4e51-bd78-a882ed33d242
.undertone.com/ Name: UID_EXT_48
Value: y-Tcj1shF1l2Yc7Li2rDA8YCq5WGgYPAj7~UP7059cced-5c7e-11eb-a84c-024b77bec4b0
.undertone.com/ Name: UID_EXT_39
Value: 85a55794-5bf1-49ae-866a-9653cfa82ecc