#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <functional>
#include <cmath>
#include <string>
#include <queue>
#include <map>
#include <bitset>
#include <set>
#include <stack>
#include <numeric>
#include <unordered_map>
#include <random>

using namespace std;

using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vd = vector<double>;
using vs = vector<string>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<double, double>;
using vpii = vector<pii>;
using vpll = vector<pll>;
using vpdd = vector<pdd>;
const int inf = (1 << 30) - 1;
const ll INF = 1LL << 60;
//const int MOD = 1000000007;
const int MOD = 998244353;

vi getPrimes(int N) {
	vector<bool> isPrime(N + 1, true);
	isPrime[0] = isPrime[1] = false;

	for (int p = 2; p * p <= N; ++p) {
		if (!isPrime[p]) continue;

		for (int q = p * 2; q <= N; q += p) {
			isPrime[q] = false;
		}
	}
	vi ret;
	ret.push_back(1);
	for (int i = 2; i < N; i++) {
		if (isPrime[i]) ret.push_back(i);
	}
	ret.push_back(N + 1);
	return ret;
}

int check(vi& cnt, vb& tgt) {
	int cnt1 = 0;
	int cnt2 = 0;
	for (int i = 0; i < 10; i++) {
		if (!tgt[i] && cnt[i] > 0) return 2;
		if (tgt[i]) {
			cnt2++;
			if (cnt[i] > 0) cnt1++;
		}
	}
	if (cnt1 < cnt2) return 1;

	return 0;
}

void count(int x, vi& cnt) {
	while (x > 0) {
		cnt[x % 10]++;
		x /= 10;
	}
}

int main() {
	int n;
	cin >> n;
	vi a(n);
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	vb tgt(10, false);
	for (int i = 0; i < n; i++) {
		tgt[a[i]] = true;
	}
	vi cnt(10, 0);
	vi p = getPrimes(5000000);
	int L = 1, K = 1, ans = -1;

	int r = 1;
	int ma = p.size() - 1;
	bool ok = false;

	while (r <= ma) {
		int ch = check(cnt, tgt);
		while (r <= ma && ch == 1) {
			count(p[r], cnt);
			ch = check(cnt, tgt);
			r++;
		}
		if (ch == 0) {
			while (r <= ma && ch == 0) {
				count(p[r], cnt);
				ch = check(cnt, tgt);
				r++;
			}
			K = p[r - 1] - 1;

			ans = max(ans, K - L);
		}

		L = p[r - 1] + 1;
		cnt.assign(10, 0);

	}
	cout << ans << endl;

	return 0;
}