C++ :

#include <cstdio>
#include <map>
#include <vector>
#include <algorithm>
using namespace std;
int main(){
    long long n; if(scanf("%lld",&n)!=1) return 0;
    map<long long,long long> cnt;
    for(long long i=0;i<n;i++){long long v;scanf("%lld",&v);cnt[v]++;}
    long long keep=0;
    for(map<long long,long long>::iterator it=cnt.begin();it!=cnt.end();++it){
        long long v=it->first, c=it->second;
        if(v<=n && c>=v) keep+=v;
    }
    printf("%lld\n", n-keep);
    return 0;
}