/in/foo.cc:2:7: error: expected nested-name-specifier before 'namepsac'
 using namepsac etsd;
       ^~~~~~~~
/in/foo.cc:3:1: error: 'string' does not name a type
 string s,c1,c2;
 ^~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:6:2: error: 'cin' was not declared in this scope
  cin>>s;
  ^~~
/in/foo.cc:6:2: note: suggested alternative:
In file included from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:75:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/iostream:60:18: note:   'std::cin'
   extern istream cin;  /// Linked to standard input
                  ^~~
/in/foo.cc:6:7: error: 's' was not declared in this scope
  cin>>s;
       ^
/in/foo.cc:10:4: error: 'c1' was not declared in this scope
    c1++;
    ^~
/in/foo.cc:12:4: error: 'c2' was not declared in this scope
    c2++;
    ^~
/in/foo.cc:14:2: error: 'cout' was not declared in this scope
  cout<<c1-c2;
  ^~~~
/in/foo.cc:14:2: note: suggested alternative:
In file included from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:75:0,
                 from /in/foo.cc:1:
/usr/include/c++/6/iostream:61:18: note:   'std::cout'
   extern ostream cout;  /// Linked to standard output
                  ^~~~
/in/foo.cc:14:8: error: 'c1' was not declared in this scope
  cout<<c1-c2;
        ^~
/in/foo.cc:14:11: error: 'c2' was not declared in this scope
  cout<<c1-c2;
           ^~