/in/foo.cc: In function 'int main()':
/in/foo.cc:6:9: error: 'cin' was not declared in this scope; did you mean 'std::cin'?
    6 |         cin>>n;
      |         ^~~
      |         std::cin
In file included from /in/foo.cc:1:
/usr/include/c++/12/iostream:60:18: note: 'std::cin' declared here
   60 |   extern istream cin;           /// Linked to standard input
      |                  ^~~
/in/foo.cc:10:17: error: 'cout' was not declared in this scope; did you mean 'std::cout'?
   10 |                 cout<<a*b<<endl;
      |                 ^~~~
      |                 std::cout
/usr/include/c++/12/iostream:61:18: note: 'std::cout' declared here
   61 |   extern ostream cout;          /// Linked to standard output
      |                  ^~~~
/in/foo.cc:10:28: error: 'endl' was not declared in this scope; did you mean 'std::endl'?
   10 |                 cout<<a*b<<endl;
      |                            ^~~~
      |                            std::endl
In file included from /usr/include/c++/12/iostream:39:
/usr/include/c++/12/ostream:688:5: note: 'std::endl' declared here
  688 |     endl(basic_ostream<_CharT, _Traits>& __os)
      |     ^~~~