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


int main() {
    int n; 
    cin >> n;
    vector<int> a(n);
    for (int i = 0; i  < n; i++) {
        cin >> a[i];
    }
    sort (a.begin(), a.end());
    int t = 0;
    int p = 0, i = 0;
    while (i < n) {
       while(p < n and a[p]-a[i] <= 1) p++;
       t = max(t, p-i);
       i++;
       p = i;
    }
    cout << t << endl;
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}