1117. Eddington Number(25)

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
bool cmp(int &a, int &b){
    return a > b;
}

int main()
{
    int n;
    cin >> n;
    vector<int> v(n);
    for(int i = 0; i < n; i++){
        cin >> v[i];
    }
    sort(v.begin(), v.end(), cmp);
    int cnt = 1;
    for (int i = 0; i < n; i++){
        if(v[i] > cnt) cnt++;
        else break;
    }
    cout << cnt - 1 << endl;

    return 0;
}