func_code_string: #include <bits/stdc++.h>   using namespace std;   long long n, x, sum = 0, sumtotal;   int main() {     cin >> n;     for (int i = 0; i < n - 1; i++) {       cin >> x;       sum += x;     }     sumtotal = n * (n + 1) / 2;     cout << sumtotal - sum << endl;   }   