#include <iostream>
#include <cstdio>
#include <vector>
#include <cstring>
#include <string>
#include <map>
#include <climits>
#include <algorithm>

using namespace std;

int main() {
    int n;
    cin >> n;
    int arr[n + 1];
    for(int i = 0; i < n; ++i) cin >> arr[i];
    sort(arr, arr + n);
    int a = 0;
    for(int i = 0; i < n; ++i) {
        int ret = 1;
        for(int j = i + 1; j < n; ++j) {
            if(abs(arr[j] - arr[i]) <= 1) ret++;
            else break;
        }
        a = max(a, ret);
    }
    cout << a << '\n';
}