func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, sum = 0, sum1 = 0;     int x;     cin >> n;     for (int i = 0; i < (int)n - 1; ++i) {       cin >> x;       sum += x;     }     for (int i = 1; i <= n; i++) sum1 += i;     cout << sum1 - sum << endl;     return 0;   }   