#include "bits/stdc++.h"
using namespace std;
#define MAX 5000001

bool dp[MAX];
vector<int> prime(){
	vector<int> ret;
	for (int i = 2; i < MAX; i++)
	{
		if (dp[i]) continue;
		ret.push_back(i);
		for (int j = i + i; j < MAX; j += i)
		{
			dp[j] = true;
		}
	}
	return ret;
}


vector<int> A(10, 0);
vector<int> num(10, 0);

void check(int a, int move){
	while (a != 0){
		num[a % 10] += move;
		a /= 10;
	}
}

int main() {
	int N;
	cin >> N;
	for (int i = 0; i < N; i++)
	{
		int temp;
		cin >> temp;
		A[temp] = 1;
	}
	vector<int> primes = prime();
	int ans = -1;
	int last = 0;
	for (int i = 0; i < primes.size(); i++)
	{
		check(primes[i], 1);
		for (int j = 0; j < 10; j++)
		{
			if (A[j]) continue;
			while (num[j] > 0)
			{
				check(primes[last], -1);
				last++;
			}
		}
		bool flag = true;
		for (int j = 0; j < 10; j++)
		{
			if (!A[j]) continue;
			if (num[j] == 0)
			{
				flag = false;
			}
		}
		if (i >= last && flag){
			int K, L;
			if (last != 0) K = primes[last - 1] + 1;
			else K = 1;
			if (i != primes.size() - 1) L = primes[i + 1] - 1;
			else L = 5000000;
			ans = max(ans, L - K);
		}
	}
	cout << ans << endl;
}