#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; 
    scanf("%d", &n);
    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);

    int max = 0, cnt = 0;
    int diff, start = a[0];
    for (int i = 1; i < n; i++) {
        diff = (start - a[i]);
        if (diff < 0) {
            diff *= -1;
        }
        if (diff <= 1) {
            cnt++;
            if (cnt > max) {
                max = cnt;
            }
        } else {
            start = a[i];
            if (cnt > max) {
                max = cnt;
            }
            cnt = 0;
        }
    }
    printf("%d", max + 1);
    return 0;
}