#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>

int main(){
    int n; 
    scanf("%d",&n);
    int i, arr[n], j, temp;
    for(i = 0; i < n ; i++)
        scanf("%d", &arr[i]);
    for(i = 1; i < n ; i++)
        for(j = 0; j < n - i; j++)
           if(arr[j] > arr[j+1])
             {
              temp = arr[j];
              arr[j] = arr[j+1];
              arr[j+1] = temp;
              }
    
    int count = 0, max_count = 0;
    for(i = 0; i < n - 1; i++)
    { count = 0;
       for(j = i + 1; j < n ; j++){
           if(arr[j] - arr[i] <= 1)
              count++;
           else
               break;
       }
        if(max_count < count)
            max_count = count;
    }
   
        printf("%d\n", max_count + 1);
    
    return 0;
}