#include <bits/stdc++.h>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int arr[110], n, i;
    cin >> n;
    for(i = 0; i < n; i++)
        cin >> arr[i];
    sort(arr, arr+n);
    queue <int> Q;
    Q.push(arr[0]);
    int res = 1;
    for(i = 1; i < n; i++)
    {
        while(!Q.empty() && arr[i]-Q.front()>1)
            Q.pop();
        Q.push(arr[i]);
        res = max(res, (int) Q.size());
    }
    cout << res;
    return 0;
}