#include <bits/stdc++.h>

using namespace std;

typedef pair<int, int> ii;

int main(){
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    int n;
    cin >> n;
    vector<int> a(n);
    for (int i = 0; i < n; i++) cin >> a[i];
    sort(a.begin(), a.end());
    int resp = 0;
    for (int i = 0; i < n; i++){
        int flag = 0;
        for (int j = i; j < n; j++){
            for (int k = j+1; k < n; k++){
                 if (abs(a[j]-a[k]) > 1){
                     flag = k;
                     break;
                 }
            }
            if (flag) break;
        }
        if (!flag) resp = max(resp, n-i);
        else resp = max(resp, flag-i);
    }
    cout << resp << endl;
    return 0;
}