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

int cmpfunc (const void * a, const void * b)
{
   return ( *(int*)a - *(int*)b );
}
int main(){
    int n,i,diff,j; 
    int c=0;
    scanf("%d",&n);
    int ans=0;
    int *a = malloc(sizeof(int) * n);
    for(int a_i = 0; a_i < n; a_i++){
       scanf("%d",&a[a_i]);
    }
    qsort(a, n, sizeof(int), cmpfunc);
    for(i=0;i<n;i++)
        {
        
        for(j=i+1;j<n;j++)
            {
              int diff=a[i]-a[j];
            if(diff<0)
                diff=diff*-1;
            if(diff<=1)
                c++;
            
            
            }
        c++;
        if(c>ans)
            ans=c;
        c=0;
    }
    printf("%d",ans);
    return 0;
}