/in/foo.cc: In function 'void put()':
/in/foo.cc:18:2: error: 'cout' was not declared in this scope
  cout<<t;
  ^~~~
/in/foo.cc:18:2: note: suggested alternative:
In file included from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:75:0,
                 from /in/foo.cc:2:
/usr/include/c++/6/iostream:61:18: note:   'std::cout'
   extern ostream cout;  /// Linked to standard output
                  ^~~~