#include <iostream>
#include <algorithm>
#include <cmath>

using namespace std;

int n;
int a[102];

int main() {
	cin >> n;
	for (int i = 1; i <= n; ++i)
		cin >> a[i];
	int ans = 0;
	for (int i = 1; i <= n; ++i) {
		int cur = 0;
		for (int j = 1; j <= n; ++j)
			if (a[j] - a[i] <= 1 && a[j] >= a[i])
				cur++;
		ans = max(ans, cur);
	}
	cout << ans << endl;
	return 0;
}