#include<bits/stdc++.h>
using namespace std;


int main()
{
    map<int, int> cnt;
    int n;
    cin >> n;
    for ( int i = 1; i <= n; i++ ) {
        int a;
        cin >> a;
        cnt[a]++;
    }

    int ans = 0;

    for ( auto u : cnt ) {
        if ( u.second >= u.first ) ans += ( u.second - u.first );
        else ans += u.second;
    }

    cout << ans << endl;
}