#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <stack>
#include <queue>
#include <functional>
#include <math.h>
#include <stdlib.h>
#include <map>
#include <sys/timeb.h>
#include <fstream>

using namespace std;

#define repr(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repr(i,0,n)
#define reprrev(i,a,b) for(int i=(int)(b)-1;i>=(int)(a);i--)
#define reprev(i,n) reprrev(i,0,n)
#define repi(itr,ds) for(auto itr=ds.begin();itr!=ds.end();itr++)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define mp make_pair
#define mt make_tuple
#define INF 1050000000
#define INFL 1100000000000000000LL
#define EPS (1e-10)
#define MOD 1000000007
#define PI 3.1415926536
#define RMAX 4294967295

typedef long long ll;
typedef pair<int, int> Pi;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<bool> vb;
typedef vector<char> vc;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<Pi> vPi;
typedef vector<vector<int> > vvi;
typedef vector<vector<bool> > vvb;
typedef vector<vector<ll> > vvll;
typedef vector<vector<char> > vvc;
typedef vector<vector<string> > vvs;
typedef vector<vector<double> > vvd;
typedef vector<vector<Pi> > vvPi;
typedef priority_queue<int, vector<int>, greater<int> > pqli;
typedef priority_queue<ll, vector<ll>, greater<ll> > pqlll;
typedef priority_queue<Pi, vector<Pi>, greater<Pi> > pqlP;
struct Edge {
	int from, to, cost;
	bool operator<(Edge e) {
		return cost < e.cost;
	}
};
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;
template <class T>
using vec = vector<T>;
template<class T>
using pql = priority_queue<T, vector<T>, greater<T>>;
string debug_show(Pi a) {
	return "(" + to_string(a.first) + "," + to_string(a.second) + ")";
}

template<class T>
struct augEdge {
	T from, to;
	int cost;
	bool operator<(augEdge e) { return cost < e.cost; }
	bool operator>(augEdge e) { return cost > e.cost; }
};
template<class T>
using augGraph = vector<augEdge<T>>;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	int n;
	cin >> n;
	vi a(n);
	map<int, int> b;
	rep(i, n) {
		int t;
		cin >> t;
		a[i] = t;
	}

	sort(all(a));

	rep(i, n) {
		b[a[i]]++;
	}

	int ans = 0;
	rep(i, n) {
		if (b[a[i]] > a[i]) {
			ans += b[a[i]]-a[i];
			b[a[i]] = 0;
		}
		else if(b[a[i]] < a[i]){
			ans += b[a[i]];
			b[a[i]] = 0;
		}
	}

	cout << ans << endl;


	/*
	string s, t;
	cin >> s >> t;
	int tmp1 = INF, tmp2 = 0;
	sort(all(s));
	sort(all(t));
	int a = min(s.size(), t.size());
	bool f = false;
	bool f2 = false;
	rep(i, a) {
		if (s[i] == t[i]) continue;
		if (s[i] < t[i]) {
			f = true;
			f2 = false;
		}
		if (s[i] > t[i]) {
			f2 = true;
		}
	}
	if (f2) {
		cout << "No" << endl;
		return 0;
	}
	if (f) {
		cout << "Yes" << endl;
	}
	else if(s.size() >= t.size()){
		cout << "No" << endl;
	}
	else
	{
		cout << "Yes" << endl;
	}
	//*/
	/*/
	rep(i, s.size()) {
		tmp1 = min((int)s[i], tmp1);
	}
	rep(i, t.size()) {
		tmp2 = max((int)t[i], tmp2);
	}

	if (tmp1 == tmp2) {
		if(s.size() < t.size()){
			cout << "Yes" << endl;
		}
		else {
			cout << "No" << endl;
		}
		
	}
	else if(tmp1 < tmp2)
	{
		cout << "Yes" << endl;
	}
	else {
		cout << "No" << endl;
	}
	//*/
	return 0;
}


Measured memory_bytes: 5120