#include <iostream>
using namespace std;
const int MAX = 1e6+1;
int count[MAX];
int main(){
    freopen("TEAM.INP",'r',stdin);
    freopen("TEAM.OUT",'w',stdout);
    int n,res=0;cin>>n;
    for (int i = 0 ; i< MAX;++i) count[i] = 0;
    for (int i = 0 ; i < n;++i){
        int x;cin>>x;
        ++count[x];
    }

    for ( int i = 1 ; i < MAX;++i) res += count[i]/i;
    cout<<res;
}