#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <cassert>
#include <limits>
#include <functional>
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#if defined(_MSC_VER) || __cplusplus > 199711L
#define aut(r,v) auto r = (v)
#else
#define aut(r,v) __typeof(v) r = (v)
#endif
#define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it)
#define all(o) (o).begin(), (o).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset(m,v,sizeof(m))
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
typedef vector<int> vi; typedef pair<int,int> pii; typedef vector<pair<int,int> > vpii; typedef long long ll;
template<typename T, typename U> inline void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> inline void amax(T &x, U y) { if(x < y) x = y; }


vector<int> primes;
vector<int> smallestPrimeFactor;
void linearSieve(int n) {
	if(n < 1) n = 1;
	if((int)smallestPrimeFactor.size() >= n+1) return;
	int primePiBound = n < 20 ? n - 1 : (int)(n / (log(n * 1.) - 2) + 2);
	primes.assign(primePiBound + 1, numeric_limits<int>::max());
	int P = 0;
	smallestPrimeFactor.assign(n + 1, 0);
	smallestPrimeFactor[1] = 1;
	int n2 = n / 2, n3 = n / 3, n5 = n / 5;
	if(n >= 2)
		primes[P ++] = 2;
	if(n >= 3)
		primes[P ++] = 3;
	for(int q = 2; q <= n; q += 2)
		smallestPrimeFactor[q] = 2;
	for(int q = 3; q <= n; q += 6)
		smallestPrimeFactor[q] = 3;
	for(int q = 5; q <= n5; q += 2) {
		if(smallestPrimeFactor[q] == 0)
			primes[P ++] = smallestPrimeFactor[q] = q;
		int bound = smallestPrimeFactor[q];
		for(int i = 2; ; ++ i) {
			int p = primes[i];
			if(p > bound) break;
			int pq = p * q;
			if(pq > n) break;
			smallestPrimeFactor[pq] = p;
		}
	}
	for(int q = (n5 + 1) | 1; q <= n; q += 2) {
		if(smallestPrimeFactor[q] == 0)
			primes[P ++] = smallestPrimeFactor[q] = q;
	}
	primes.resize(P);
}

int getdigits(int x) {
	int r = 0;
	while(x > 0)
		r |= 1 << (x % 10), x /= 10;
	return r;
}

int main() {
	const int X = 5000000;
	linearSieve(X + 1000);
	int N;
	while(cin >> N) {
		int des = 0;
		rep(i, N) {
			int A;
			cin >> A;
			des |= 1 << A;
		}
		int ans = -1;
		int cnt[10] = {};
		for(int i = 0, j = 0; primes[i] <= X; ++ i) {
			for(; primes[j] < X; ++ j) {
				int t = getdigits(primes[j]);
				if(t & ~des) break;
				rep(d, 10) if(t >> d & 1) ++ cnt[d];
			}
			if(i < j && 10 - count(cnt, cnt + 10, 0) == N)
				amax(ans, min(X, primes[j] - 1) - (i == 0 ? 1 : primes[i-1] + 1));
			if(i == j) {
				++ j;
			}else {
				int t = getdigits(primes[i]);
				rep(d, 10) if(t >> d & 1) -- cnt[d];
			}
		}
		cout << ans << endl;
	}
	return 0;
}