/in/foo.cc: In function 'int main()':
/in/foo.cc:5:1: error: 'longlong' was not declared in this scope
 longlong N,a,b;
 ^~~~~~~~
/in/foo.cc:6:6: error: 'a' was not declared in this scope
 cin>>a>>b;
      ^
/in/foo.cc:6:9: error: 'b' was not declared in this scope
 cin>>a>>b;
         ^