// fest
#include <bits/stdc++.h>	

#define pb push_back
#define F first
#define S second
#define y1 dasdasfasfas
#define x1 wqdadfasfasfas
#define All(c) c.begin(), c.end()
#define SZ(A) (int((A).size()))
#define umap unordered_map
#define __ fflush(stdout)

typedef long long ll;
typedef long double ld;    

using namespace std;

inline double Time() {return (clock() * 1.0) / CLOCKS_PER_SEC; }             

const int N = 200500, inf = 1e9 * 2, MOD = 1e9 + 7;

char CH[N];

const ll INF = 1e18;

const int dx[] = {1, -1, 0, 0, -1, 1, -1, 1};
const int dy[] = {0, 0, 1, -1, -1, 1, 1, -1};

int a[N];

int main() {

	unsigned int FOR;
	asm("rdtsc" : "=A"(FOR));
	srand(FOR);
	int n;
	cin >> n;
	for (int i = 1; i <= n; i++) cin >> a[i];
	int ans = 0;
	for (int i = 1; i < 100; i++) {
		int now = 0;
		for (int j = 1; j <= n; j++) {
			if (i - a[j] <= 1 && i - a[j] >= 0) now++;	
		}
		ans = max(ans, now);
	}
	cout << ans;
	return 0;
}