import java.util.Arrays;
import java.util.Scanner;

public class Question1 {

    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();
        }
        
        Arrays.sort(a);
        
        getMax(a);
        
    }

    private static void getMax(int[] a) {
        // TODO Auto-generated method stub
        int max = 1;
        
        for (int i = 0; i < a.length; i++) {
            int tempMax=1;
            int leftMax, rightMax;
            int leftIndex=i-1;
            int rightIndex=i+1;
            
            for (int j = i-1; j >=0; j--) {//get leftIndex                
                if (a[i]-a[j]==0) {
                    tempMax++; 
                    leftIndex--;
                }else{
                    break;
                }               
            }
            
            for (int j = i+1; j < a.length; j++) {////get rightIndex                
                if (a[j]-a[i]==0) {
                    tempMax++; 
                    rightIndex++;
                }else{
                    break;
                }
            }
            
            leftMax = tempMax;
            rightMax = tempMax;
            //System.out.println("init:"+tempMax);
            //System.out.println(leftIndex+" "+rightIndex);            
            
            
            for (int j = leftIndex; j >=0; j--) {//left
                if (a[i]-a[j]<=1) {
                    leftMax++;
                }else{
                    break;
                }               
            }
                        
            
            for (int j = rightIndex; j < a.length; j++) {//right
                if (a[j]-a[i]<=1) {
                    rightMax++;
                }else{
                    break;
                }
            }
            
            //System.out.println(leftMax+" "+rightMax);
            
            tempMax = leftMax>rightMax?leftMax:rightMax;
            max = max>tempMax?max:tempMax;
        }
        
        System.out.println(max);
    }

}