/in/foo.cc: In function 'int main()':
/in/foo.cc:8:3: error: expected initializer before 'cin'
   cin>>a>>b;
   ^~~
/in/foo.cc:9:10: error: 'b' was not declared in this scope
  cout<<a+b<<endl;
          ^
/in/foo.cc:10:5: error: 'retern' was not declared in this scope
     retern 0;
     ^~~~~~