#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
const int MAX = 200;
int a[MAX];

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int n;
    cin >> n;
    for(int i=0;i<n;i++) cin >> a[i];
    int ret = 0;
    for(int i=0;i<=100;i++){
        int tmp = 0;
        for(int j=0;j<n;j++){
            if(a[j] == i || a[j] == i+1) tmp++;
        }
        ret = max(ret, tmp);
    }
    cout << ret;
    return 0;
}