#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

int A[100];
int n;

void enter() {
    cin >> n;
    for (int i = 0; i < n; ++i) cin >> A[i];
}

void solve() {
    int res = 0;
    for (int i = 0; i < n; ++i) {
        res = max(res, (int)(count(A, A + n, A[i]) + max(count(A, A + n, A[i] - 1), count(A, A + n, A[i] + 1))));
    }
    
    cout << res << "\n";
}

int main() {
    enter();
    solve();
    return 0;
}