foo.cc: In function 'bool check(int)':
foo.cc:13:5: error: 'memset' was not declared in this scope
   13 |     memset(p,0,sizeof(p));
      |     ^~~~~~
foo.cc:2:1: note: 'memset' is defined in header '<cstring>'; did you forget to '#include <cstring>'?
    1 | #include <iostream>
  +++ |+#include <cstring>
    2 | #include <string>

[Hydro](https://hydro.ac)提供评测服务