/in/foo.cc: In function 'int main()':
/in/foo.cc:12:20: warning: variable 'xx' set but not used [-Wunused-but-set-variable]
  double x, y, ans, xx;
                    ^~
/in/foo.cc:29:23: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
  printf("%.0f\n", ans);
                       ^