#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;

/*
sample input:
7
9 10 11 3 4 5 8

sample input:
6
4 6 5 3 3 1
sample output:
3
*/
int main() {
    int n;
    cin >> n;
    vector<int> a(n);

    int i;
    for (i = 0; i < n; i++) {
        cin >> a[i];
    }

    sort(a.begin(), a.end());
    int maxV = 0;
    for (i = 0; i < n; i++) {
        int j;
        for (j = i + 1; j < n; j++)
            if (a[j] - a[i] > 1)
                break;

        maxV = max(maxV, j - i);
    }

    cout << maxV << endl;

    return 0;
}