/in/foo.cc:14:7: error: expected nested-name-specifier before 'namesapce'
 using namesapce std;
       ^~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:17:2: error: 'cin' was not declared in this scope
  cin>>a;
  ^~~
/in/foo.cc:17:2: note: suggested alternative:
In file included from /in/foo.cc:12:0:
/usr/include/c++/6/iostream:60:18: note:   'std::cin'
   extern istream cin;  /// Linked to standard input
                  ^~~
/in/foo.cc:19:2: error: 'cout' was not declared in this scope
  cout<<tmp<<endl;
  ^~~~
/in/foo.cc:19:2: note: suggested alternative:
In file included from /in/foo.cc:12:0:
/usr/include/c++/6/iostream:61:18: note:   'std::cout'
   extern ostream cout;  /// Linked to standard output
                  ^~~~
/in/foo.cc:19:13: error: 'endl' was not declared in this scope
  cout<<tmp<<endl;
             ^~~~
/in/foo.cc:19:13: note: suggested alternative:
In file included from /usr/include/c++/6/iostream:39:0,
                 from /in/foo.cc:12:
/usr/include/c++/6/ostream:590:5: note:   'std::endl'
     endl(basic_ostream<_CharT, _Traits>& __os)
     ^~~~