import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    private static int count(int[] array){
        int sum = 0;
        
        for(int i=0;i<array.length;i++){
            int pSum=0;
            int nSum=0;
            for(int j=0;j<array.length;j++){
                int temp = array[i]-array[j];
                if(temp<=1&&temp>=0){      
                    pSum++;
                }else if(temp>=-1&&temp<=0){ 
                    nSum++;
                }
                
            }
            if(pSum>sum){
                sum=pSum;
            }
            if(nSum>sum){
                sum=nSum;
            }
        }
        
        return sum;
        
    }
    
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] array = new int[n];
        for(int i=0; i < n;i++){
            array[i] = in.nextInt();
        }
        
        System.out.println(count(array));
        
    }
}