#include <cmath>
#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 n;
    cin >> n;
    int a[n],c = 0;
    for (int i = 0; i < n; i++) cin >> a[i];
    sort(a, a + n);
    int mx = 0;
    for (int i = 0; i < n - 1; i++) {
        int x = a[i], y = a[i + 1], c = 0;
                if (y - x > 1) continue;
        for (int j = 0; j < n; j++) {
            if (a[j] == x or a[j] == y)  {
                c++;
            }
        }
        mx = max(c, mx);
    }
    for (int j = 0; j < n; j++) {
      c = 0;
      for (int i = 0; i < n; i++) {
          c += (a[i] == a[j]);
      }
      mx = max(c, mx);
    }
    cout << mx << endl;
    return 0;
}