Reading state information... Done

The following additional packages will be installed:
  g++-5 libstdc++-5-dev
Suggested packages:
  g++-multilib g++-5-multilib gcc-5-doc libstdc++6-5-dbg libstdc++-5-doc
The following NEW packages will be installed:
  g++ g++-5 libstdc++-5-dev
0 upgraded, 3 newly installed, 0 to remove and 11 not upgraded.
Need to get 9738 kB of archives.
After this operation, 39.1 MB of additional disk space will be used.
Err:1 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 libstdc++-5-dev amd64 5.4.0-6ubuntu1~16.04.11
  404  Not Found [IP: 91.189.88.31 80]
Err:2 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 g++-5 amd64 5.4.0-6ubuntu1~16.04.11
  404  Not Found [IP: 91.189.88.31 80]
Get:3 http://archive.ubuntu.com/ubuntu xenial/main amd64 g++ amd64 4:5.3.1-1ubuntu1 [1504 B]
Fetched 1504 B in 0s (2852 B/s)
E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/g/gcc-5/libstdc++-5-dev_5.4.0-6ubuntu1~16.04.11_amd64.deb  404  Not Found [IP: 91.189.88.31 80]

E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/g/gcc-5/g++-5_5.4.0-6ubuntu1~16.04.11_amd64.deb  404  Not Found [IP: 91.189.88.31 80]

E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
Exited with code 100