#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
int a[105];
int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
    int n;
    cin>>n;
    for(int i=1;i<=n;i++)cin>>a[i];
    sort(a+1,a+1+n);
    int mx=-1;
    for(int i=1;i<=n;i++){
        int cur=1;
        for(int j=i+1;j<=n;j++){
            if(a[j]-a[i]>1)break;
            cur++;
        }
        mx=max(mx,cur);
    }
    cout<<mx;
    return 0;
}