// Made By Haireden Aibyn
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <string>
#include <cstdio>
#include <vector>
#include <cmath>
#include <ctime>
#include <queue>
#include <deque>
#include <stack>
#include <map>
#include <set>

using namespace std;

#define fname ""
#define INF 2147483647
#define MOD 1000000007
#define mp make_pair
#define F first
#define S second
#define sc scanf
#define all(x) x.begin(), x.end()
#define size(x) int(x.size())
#define pr printf
#define deb(x) cerr << " | " << #x << " = " << x
#define pb push_back
#define ex exit(0)
#define tim printf("%.4lf\n", (clock() * 1.) / CLOCKS_PER_SEC)
#define cas printf(""), ex;
#define y1 y4

typedef long long ll;
typedef unsigned long long ull;

const int N = 100500;

int a[N];

int main() {
    srand(time(NULL));
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    sort(a + 1, a + 1 + n);
    int ans = 1;
    for (int l = 1; l <= n; l++) {
        for (int r = l + 1; r <= n; r++) {
            if (a[r] - a[l] <= 1) ans = max(ans, r - l + 1);
        }
    }
    cout << ans;
    return 0;
}