#include<iostream>
#include<math.h>
#include<algorithm>
#include<stdint.h>
#include<vector>
#include<deque>
#include<stack>
#include<functional>
#include<string>
#include<numeric>
#include<cstring>
#include<random>
#include<array>
#include<fstream>
#include<iomanip>
#include<list>
#include<set>
#include<map>
#include<unordered_map>
#include<unordered_set>
#include<bitset>
#include<queue>

/*
#include<boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
*/

using namespace std;

using ll = long long;
using ull = unsigned long long;

#define REP(i,a,b) for(ll i = a; i < b; ++i)
#define PRI(s) std::cout << s << endl
#define PRIF(v, n) printf("%."#n"f\n", (double)v)

template<typename A, typename B>void mins(A& a, const B& b) { a = min(a, (A)b); };
template<typename A, typename B>void maxs(A& a, const B& b) { a = max(a, (A)b); };


int main() {

	ll N; cin >> N;
	unordered_set<ll> s;
	REP(i, 0, N) {
		ll a; cin >> a;
		s.insert(a);
	}

	vector<bool> E(5000001, true);
	E[0] = false;
	E[1] = false;
	REP(i, 2, 5000001) {
		if (!E[i]) continue;
		for (ll j = 2; i * j < E.size(); ++j) E[i * j] = false;
	}

	ll ans = -1;
	
	ll R = 1;
	REP(L, 1, 5000001) {
		if (L < R) continue;

		unordered_set<ll> tmp;
		for (R = L; R < 5000001; ++R) {
			if (E[R]) {
				ll t = R;
				while (t > 0) {
					if (s.count(t % 10) == 0) goto LOOPEND;
					tmp.insert(t % 10);
					t /= 10;
				}
			}
			if (s.size() == tmp.size())maxs(ans, R - L);
		}
	LOOPEND:
		continue;
	}
	PRI(ans);
	return 0;
}