#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,*ar=NULL,i,count=0,pre=0,max=0;
    cin>>n;
    ar=new int[n];
    for(i=0;i<n;i++)cin>>ar[i];
    sort(ar,ar+n);
    for(i=0;i<n-1;i++){
        if((pre+abs(ar[i]-ar[i+1]))<=1){count++,pre=pre+abs(ar[i]-ar[i+1]);}
        else count=0,pre=0;
        
        if(count>max)max=count;
    }
    cout<<max+1<<endl;
    return 0;
}