/in/foo.cc: In function 'int main()':
/in/foo.cc:6:2: error: expected ';' before 'string'
  string a;
  ^~~~~~
/in/foo.cc:7:8: error: 'a' was not declared in this scope
  cin<< a;
        ^
/in/foo.cc:8:7: error: expected '}' at end of input
  a=a+1;
       ^