6:4

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n;
    cin>>n;
    vector<int>v(n);
    for(int i=0;i<n;i++)
    {
        cin>>v[i];
    }
    map<int,int>mp;
    for(auto u:v)
    {
        mp[u]++;
    }
    int coun=0;
    for(auto u:mp)
    {
        if(u.first<u.second)
        {

            coun+=abs(u.first-u.second);
        }
        else if(u.first>u.second) coun+=u.second;
    }
   cout<<coun;
}