/in/foo.cc: In function 'int main()':
/in/foo.cc:56:5: error: 'memset' was not declared in this scope
   56 |     memset(tree, -1, sizeof(tree));
      |     ^~~~~~
/in/foo.cc:6:1: note: 'memset' is defined in header '<cstring>'; did you forget to '#include <cstring>'?
    5 | #include <cmath>
  +++ |+#include <cstring>
    6 | using namespace std;