foo.cc: In function 'int main()':
foo.cc:17:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   17 |         scanf("%d%d",&n,&m);
      |         ~~~~~^~~~~~~~~~~~~~

正在同步测试数据，请稍后
[Hydro](https://hydro.ac)提供评测服务