#include <iostream>
#include <vector>

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;
    vector<int> fa(n + 1);
    vector<vector<int>> vec(n + 1);
    vector<bool> chk1(n + 1, 1), chk2(n + 1, 0);
    for (int i = 1; i <= n; i++) {
        cin >> fa[i];
        if (!fa[i]) continue;
        vec[fa[i]].push_back(i);
        chk1[fa[i]] = 0;
    }
    for (int i = 1; i <= n; i++) {
        for (auto j : vec[i]) {
            if (chk1[j]) {
                chk2[i] = 1;
                break;
            }
        }
    }
    int tot = 0;
    for (int i = 1; i <= n; i++) {
        for (auto j : vec[i]) {
            if (chk2[j]) {
                tot++;
                break;
            }
        }
    }
    cout << tot << endl;
    return 0;
}