#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+1];
    int b[n+1],count,m=0;
    for(int i=0;i<n;i++)
        cin>>a[i];
    sort(a,a+n);
    for(int i=0;i<n;i++)
        {
        count=1;
            for(int j=i+1;j<n;j++)
            {
                if(a[j]-a[i]<=1)
                    count++;
                else
                    break;
            }
        m=max(m,count);
    }
    cout<<m;
    return 0;
}