/usr/share/man/man1/cpp-8.1.gz is in cpp-8 8-20180414-1ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man1/x86_64-linux-gnu-cpp-8.1.gz
/usr/share/man/man1/x86_64-linux-gnu-cpp-8.1.gz