foo.cc: In function 'int main()':
foo.cc:21:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   21 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
foo.cc:24:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   24 |         scanf("%d", &a[i]);
      |         ~~~~~^~~~~~~~~~~~~
foo.cc:33:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   33 |         scanf("%d%d%d%d", &opt, &l, &r, &c);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

正在同步测试数据，请稍后
Found 10 testcases.
[Hydro](https://hydro.ac)提供评测服务