/in/foo.cc:2:2: error: 'cin' does not name a type
  cin>> x;
  ^~~
/in/foo.cc:3:2: error: expected unqualified-id before 'while'
  while(x!=0) 
  ^~~~~
/in/foo.cc:8:2: error: 'cout' does not name a type
  cout<<sum;
  ^~~~