/***************************************************\
*               Mir Abdullah yousuf                 *
*    Khulna University of Engineering & Technology  *
*     Electrical and Electronic Engineering, 2k14   *
\***************************************************/
#include <bits/stdc++.h>
#define LL              long long
#define PI              acos(-1.0)
#define PII             pair<int,int>
#define ff              first
#define ss              second
#define MS(a,b)         memset(a, b, sizeof (a))
#define MP(a,b)         make_pair(a, b)
#define sf(a)           scanf("%d", &a)
#define sff(a, b)       scanf("%d %d", &a, &b)
#define sfff(a, b, c)   scanf("%d %d %d", &a, &b, &c)
#define sfl(a)          scanf("%lld", &a)
#define sfll(a, b)      scanf("%lld %lld", &a, &b)
#define sflll(a, b, c)  scanf("%lld %lld %lld", &a, &b, &c)
#define READ()          freopen("input.txt", "r", stdin)
#define WRITE()         freopen("output.txt", "w", stdout)
#define GCD(a, b)       __gcd(a, b)
#define sqr(a)          (a) * (a)
#define MOD             10000007
#define MAX             100000
using namespace std;

///***********-8-direction*************/
//int fx[] = {1, -1, 0, 0, 1, -1, -1, 1};
//int fy[] = {0, 0, 1, -1, 1, 1, -1, -1};

///***********-4-direction*************/
//int fx[] = {1, -1, 0, 0};
//int fy[] = {0, 0, 1, -1};

int chk[110];

int main()
{
    int n;
    sf(n);
    int ara[n];

    for (int i = 0; i < n; i++) {
        sf(ara[i]);
        chk[ara[i]]++;
    }

    int mx = 0, cnt = 0, x;

    for (int i = 1; i <= 100; i++) {
        x = chk[i] + chk[i - 1];
        mx = max(mx, x);
    }
    cout << mx << endl;
    return 0;
}