/in/foo.cc: In function 'long long int C(long long int, long long int)':
/in/foo.cc:6:2: error: '_int128' was not declared in this scope
  _int128 x=1,y=1;
  ^~~~~~~
/in/foo.cc:9:6: error: 'x' was not declared in this scope
      x*=(n-i);y*=(i+1);
      ^
/in/foo.cc:9:15: error: 'y' was not declared in this scope
      x*=(n-i);y*=(i+1);
               ^
/in/foo.cc:11:9: error: 'x' was not declared in this scope
  return x/y;
         ^
/in/foo.cc:11:11: error: 'y' was not declared in this scope
  return x/y;
           ^