#include<bits/stdc++.h>
using namespace std;
const int N=1e5+10;
int ans,a[N];
int main()
{
	int n;scanf("%d",&n);
	for(int i=1;i<=n;i++)scanf("%d",&a[i]);
	sort(a+1,a+n+1);
	for(int i=1;i<=n;i++)
	{
		int sum=1;
		while(i<n&&a[i+1]==a[i])i++,sum++;
		if(sum<a[i])ans+=sum;
		else ans+=sum-a[i];
	}
	printf("%d\n",ans);
	return 0;
}