#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 max1=-1;
    int arr[111];
    for(int i=0;i<n;i++)
        cin>>arr[i];
    sort(arr,arr+n);
    for(int i=0;i<n;i++)
    {
        int j=i;
        int ctr=0;
        while(j<n && (arr[j]-arr[i])<=1)
        {
            ctr++;
            j++;
        }
        max1=max(max1,ctr);
    }
    cout<<max1<<endl;
    return 0;
}