/in/foo.cc: In function 'int main()':
/in/foo.cc:9:32: error: 'memset' was not declared in this scope
  memset(ans_t, 0, sizeof(ans_t));
                                ^
/in/foo.cc:11:18: warning: unused variable 'k' [-Wunused-variable]
  int d, n, x, y, k, x1, x2, y1, y2, a;
                  ^