#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pii> P;

const ll INF = 1ll<<29;
const ll MOD = 1000000007;
const double EPS  = 1e-10;

vector<int> sieve(int n) {
	vector<int> res;
	vector<bool> is_prime(n + 1, true);
	
	is_prime[0] = is_prime[1] = false;
	
	for (int i = 2; i * i <= n; i++) if (is_prime[i]) {
		res.push_back(i);
		is_prime[i] = false;
		for (int j = 2; i * j <= n; j++) if (is_prime[i * j]) {
			is_prime[i * j] = false;
		}
	}
	
	REP(i, n + 1) if (is_prime[i]) res.push_back(i);
	sort(res.begin(), res.end());
	return res;
}

int cnt[350000][10];

int main() {
	int n, a[10];
	
	cin >> n;
	REP(i, n) scanf("%d", a + i);
	
	int s = 0;
	REP(i, n) s |= 1<<a[i];
	
	vector<int> prime = sieve(5000000);
	
	REP(i, prime.size()) {
		REP(j, 10) cnt[i + 1][j] = cnt[i][j];
		
		stringstream ss; ss << prime[i];
		string str = ss.str();
		REP(j, str.size()) cnt[i + 1][str[j] - '0']++;
	}
	
	int ans = -1;
	
	int l = 0;
	REP(i, prime.size()) {
		while (l <= i) {
			bool ok = true;
			
			REP(j, 10) if (!(s >> j & 1) && cnt[i + 1][j] - cnt[l][j] > 0) ok = false;
			
			if (ok) break;
			l++;
		}
		
		bool ok = true;
		REP(j, 10) if ((s >> j & 1) && cnt[i + 1][j] - cnt[l][j] == 0) ok = false;
		
		if (ok) {
			int ma = i == prime.size() - 1 ? 5000000 : prime[i + 1] - 1;
			int mi = l == 0 ? 1 : prime[l - 1] + 1;
			
			chmax(ans, ma - mi);
		}
	}
	
	cout << ans << endl;
	
	return 0;
}