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


int main() {
    int n;
    scanf("%d",&n);
    int arr[n];
    int i,j,c=0,max=0;
    for(i=0;i<n;i++)
        scanf("%d",&arr[i]);
    sort(arr,arr+n);
    for(i=0;i<n-1;i++)
        {
        for(j=i+1;j<n;j++)
            {
            if(abs(arr[i]-arr[j])<=1)
                c++;
            else
                break;
        }
        if(max<c)
            max=c;
            c=0;
    }
    printf("%d",max+1);
    
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}