answer.code: In function ‘int main()’:
answer.code:42:9: error: ‘memset’ was not declared in this scope
   42 |         memset(nd, -1, sizeof nd);
      |         ^~~~~~
answer.code:8:1: note: ‘memset’ is defined in header ‘<cstring>’; did you forget to ‘#include <cstring>’?
    7 | #include <cassert>
  +++ |+#include <cstring>
    8 | 
answer.code:64:18: warning: structured bindings only available with ‘-std=c++17’ or ‘-std=gnu++17’ [-Wc++17-extensions]
   64 |         for(auto [x, y] : A) cout << y << ' ' << x << ' ' << y << '\n';
      |                  ^