func_code_string: #include <bits/stdc++.h>   using namespace std;   bool check(vector<int> &a) { return a[0] + a[1] + a[2] == a[3] + a[4] + a[5]; }   signed main() {     int n;     cin >> n;     vector<int> a(n, 0);     for (int i = 0; i < n; ++i) cin >> a[i], --a[i];     vector<int> used(n, 0);     int cnt = 0;     for (int i = n - 1; i > -1; --i) {       if (!used[i]) {         used[i] = 1;         int c = i;         while (a[c] > -1 && !used[a[c]]) used[a[c]] = 1, c = a[c];         ++cnt;       }     }     cout << cnt << endl;     return 0;   }   