#include<bits/stdc++.h>                               
using namespace std;

#define PI acos(-1)
#define fi first
#define se second
#define pb push_back
#define sz(a) (int)(a).size()
#define all(c) (c).begin(), (c).end()
#define TIMESTAMP fprintf(stderr, "Execution time: %.3lf s.\n", (double)clock()/CLOCKS_PER_SEC)

typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair <int, int> pii;
typedef vector <vi> vvi;
typedef vector <pii> vpii;
typedef vector<string> vs;

const int INF = 100500;
const int MAXN = 1e2 + 9;

int n, aa[MAXN];

void input() {
	cin >> n;
	for(int i = 0; i < n; i++) cin >> aa[i];
	sort(aa, aa + n);
}

void solve() {
	int ans = 0;
	int r = 0;
	for(int i = 0; i < n; i++) {
		while(r < n - 1 && aa[r + 1] - aa[i] <= 1) r++;
		ans = max(ans, r - i + 1);
	}
	cout << ans << endl;
}

int main() {
#ifdef LOCAL
	freopen("xxx.in", "r", stdin);
	freopen("xxx.out", "w", stdout);
#else
	//freopen("xxx.in", "r", stdin);
	//freopen("xxx.out", "w", stdout);
#endif	
	input();
	solve();
	return 0;
}