#include <iostream>
#include <vector>
#include <string>
#include <cstring>
using namespace std;

const int kMaxNumber = 5000000;

bool prime_table[kMaxNumber + 1];
bool should_use[10];

int main() {
    // Eratosthenesの篩
    fill(prime_table, prime_table + kMaxNumber + 1, true);
    prime_table[0] = prime_table[1] = false;
    
    for (int n = 2; n * n <= kMaxNumber; n++) {
        if (prime_table[n]) {
            for (int i = 2; i * n <= kMaxNumber; i++) {
                prime_table[i * n] = false;
            }
        }
    }

    int N;
    cin >> N;
    for (int i = 0; i < N; i++) {
        int A;
        cin >> A;
        should_use[A] = true;
    }

    int s = 1, ans = -1;
    while (s <= kMaxNumber) {
        int t = s;
        bool used[10] = {false};

        while (t <= kMaxNumber) {
            if (prime_table[t]) {
                // 使ってもいい素数かどうか
                bool ok = true;
                string str = to_string(t);
                for (int i = 0; i < str.size(); i++) {
                    ok = ok && should_use[str[i] - '0'];
                }
                if (!ok) break;

                for (int i = 0; i < str.size(); i++) {
                    used[str[i] - '0'] = true;
                }
            }
            t++;
        }
        bool valid = true;
        for (int d = 0; d < 10; d++) {
            valid = valid && (!should_use[d] || used[d]);
        }

        if (valid) ans = max(ans, t - s - 1);
        s = t + 1;
    }

    cout << ans << endl;

    return 0;
}