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

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] a = new int[n];
        for(int a_i=0; a_i < n; a_i++){
            a[a_i] = in.nextInt();
        }
        
        int max_count = 0;
        
        for( int i=0;i< n;i++){
            
            int count = 1;
            
            for( int j=0;j<n;j++){
                if( i == j )
                    continue;
                
                if( a[i]-a[j] <= 1 && a[i]-a[j] >= 0 ){
                    count++;
                    //System.out.println( a[i] + " - " + a[j] + " <= 1" );
                }
            }
            
            if( count > max_count )
                max_count = count;
            
            //System.out.println( max_count );
            
            count = 1;
            
            for( int j=0;j<n;j++){
                if( i == j )
                    continue;
                
                if( a[i]-a[j] >= -1 && a[i]-a[j] <= 0 ){
                    count++;
                }
            }
            
            if( count > max_count )
                max_count = count;
            
            //System.out.println( max_count );
        }
        
        System.out.println( max_count );
    }
}