#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,c=0,maxi=0;
    
    cin>>n;
    
    int A[n];
    
    
    for(int i=0;i<n;i++)
           cin>>A[i];
    
    
    sort(A,A+n);
    
    
    for(int i=0;i<n;i++)
    {
        c=1;
        for(int j=i+1;j<n;j++)
        {
            if(fabs(A[i]-A[j])<=1)
                c++;
            else
                break;
        }
        
        if(c>maxi)
            maxi=c;
    }
    
    
    
    
    cout<<maxi<<endl;
    return 0;
}