#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 i;
    int a[n];
    int h = 0;
    for(i = 0;i < n;i++)
        cin>>a[i];
    sort(a,a+n);
    int j, t;
    t = -1;
    for(i = 0; i <= n - 1;i++)
        {
        h = 0;
        for( j = i;j <=  n -1 ;j++)
            {
        if(abs(a[j] - a[i]) <= 1)
            h++;
        }
        if(h > t)
            t = h;
    }
    cout<<t;
    return 0;
}