func_code_string: #include <bits/stdc++.h>   using namespace std;   const int MX = 1000001;   const int MI = 100001;   const int MT = 10001;   int main() {     long long int n, ans = 0;     cin >> n;     ans = (n * (n + 1)) / 2;     n--;     for (int i = 0; i < n; ++i) {       int x;       scanf( %d , &x);       ans -= x;     }     cout << ans << endl;     return 0;   }   