#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <fstream>
#include <sstream>
#include<set>
#include<stack>
#include<time.h>
#include <sys/types.h>
#include <tuple>
#include <numeric>
#include <iterator>

typedef long long int ll;
//#include<bits/stdc++.h>


using namespace std;

ll gcd(ll a, ll b) {
    if (a < b)swap(a, b);
    if (b == 0)return a;
    return gcd(b, a % b);
}
int lcm(int a, int b) {
    return a * b / gcd(a, b);
}


int main()
{

    int Q;
    Q = 1;
    //cin >> Q;


    while (Q--) {
        int n;
        cin >> n;
        int ans = 0;
        vector<int>p(n);
        vector<int>t(n);
        for (int i = 0; i < n; i++) {
            cin >> p[i]; t[i] = i;
        }
        sort(p.begin(), p.end());
        for (int i = 0; i < n; i++) {
            for (int j = i + 1; j < n; j++) {
                if (p[i] + 1 >= p[j])continue;
                t[i] = j; break;
            }
        }
        for (int i = 0; i < n; i++) {
            //cout << p[i] << " " << t[i] << endl;
            if (t[i] == i)ans++;
        }
        cout << ans;
    }
    return 0;
}