#include <bits/stdc++.h>
#define rep(i,l,r) for(int i=l; i<=r; i++)
#define per(i,r,l) for(int i=r; i>=l; i--)
#define IOS {cin.tie(0);cout.tie(0);ios::sync_with_stdio(0);}
using namespace std;

typedef long long ll;
typedef pair<int,int> P;

int a[100], vis[100];
bool prime(int x) {
    for (int j=2; j * j <= x; j++) {
        if (x % j == 0) return false;
    }
    return true;
}
bool check(int x) {
    while (x) {
        if (vis[x%10]) return false;
        x/=10;
    }
    return true;
}
int main() {
    int n; 
    scanf("%d", &n);
    rep (i, 1, n) scanf("%d", &a[i]), vis[a[i]] = 1;
    rep (i, 2, 10000) {
        if (check(i) && prime(i)) {
            cout <<i;
            return 0;
        }
    }
    cout << -1;
    return 0;
}