/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2020.05.20 23:18:04
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

int main() {
    int n;
    cin >> n;
    int s = 0;
    vector< bool > a(10, false);
    for (int i = 0; i < n; i++) {
        int k;
        cin >> k;
        s |= (1 << k);
        a[k] = true;
    }
    const int N = 5000000;
    // エラトステネスの篩 O(NloglogN)
    // N以下の素数
    vector< bool > isprime(N + 1, true);
    isprime[0] = isprime[1] = false;
    for (int i = 2; i * i <= N; i++) {
        if (isprime[i]) {
            for (int j = i + i; j <= N; j += i) {
                isprime[j] = false;
            }
        }
    }
    int ans = -1;
    int l = 1, r = 1;
    int m = 0;
    for (int i = 2; i <= N; i++) {
        if (i == N && m == s) {
            if (ans < N - l) {
                //cout << l << "->" << i << endl;
                ans = N - l;
            }
            // ans = max(ans, N - l);
            break;
        }
        if (isprime[i]) {
            int k = i;
            r = i;
            bool ok = true;
            int t = 0;
            while (k) {
                if (!a[k % 10]) {
                    ok = false;
                }
                t |= (1 << (k % 10));
                k /= 10;
            }
            if (!ok) {
                if (m == s) {
                    if (ans < r - l - 1) {
                        //cout << l << "->" << r - 1 << endl;
                        ans = r - l - 1;
                    }
                    // ans = max(ans, r - l - 1);
                }
                l = i + 1;
                m = 0;
            }
            else {
                m |= t;
            }
        }
    }
    cout << ans << endl;
    return 0;
}