#include <bits/stdc++.h>

using namespace std;

typedef pair<int, int> pii;
typedef long long ll;
const int N = 2000086, MOD = 1e9 + 7, INF = 0x3f3f3f3f;
ll res;
int n, m, cnt, w[N];



bool st[N], st1[N], st2[N];
int main() {
    cin >> n;
    for (int i = 1; i < n + 1; i++) scanf("%d", w + i), st[i] = 1;
    for (int i = 1; i < n + 1; i++) st[w[i]] = 0;
    for (int i = 1; i < n + 1; i++)
        if (st[i] && w[i])
            st1[w[i]] = 1;
    for (int i = 1; i < n + 1; i++)
        if (st1[i] && w[i]) {
            res += !st2[w[i]];
            st2[w[i]] = 1;
        }
    printf("%lld\n", res);
    return 0;
}