answer.code: In function ‘int main()’:
answer.code:9:5: error: ‘cin’ was not declared in this scope
    9 |     cin.tie(0)->sync_with_stdio(0);
      |     ^~~
answer.code:12:9: error: ‘i’ was not declared in this scope
   12 |     rep(i, 0, n) {
      |         ^
answer.code:12:5: error: ‘rep’ was not declared in this scope; did you mean ‘rp’?
   12 |     rep(i, 0, n) {
      |     ^~~
      |     rp
answer.code:21:9: error: ‘pi’ was not declared in this scope
   21 |     rep(pi, 1, n+1) {
      |         ^~
answer.code:45:5: error: ‘cout’ was not declared in this scope
   45 |     cout << ans << '\n';
      |     ^~~~