import java.util.*;

public class Main {
    static int[] arr;
    static int n;
    static boolean[] used;
    static TreeSet<Long> numbers = new TreeSet<>();
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        arr = new int[n];
        used = new boolean[n];
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
        }
        make(1, 0, used);
        for (long x : numbers) {
            x *= -1;
            if (isPrime(x)) {
                System.out.println(x);
                return;
            }
        }
        System.out.println(-1);
    }
    
    static void make(int count, long value, boolean[] used) {
        if (count > n) {
            numbers.add(-value);
            return;
        }
        int prev = 0;
        for (int i = n - 1; i >= 0; i--) {
            if (!used[i]) {
                if (prev == arr[i]) {
                    continue;
                }
                prev = arr[i];
                used[i] = true;
                long next;
                if (arr[i] >= 10) {
                    next = value * 100 + arr[i];
                } else {
                    next = value * 10 + arr[i];
                }
                make(count + 1, next, used);
                used[i] = false;
            }
        }
    }
    
    static boolean isPrime(long x) {
        if (x % 2 == 0) {
            return false;
        }
        for (int i = 3; i <= Math.sqrt(x); i += 2) {
            if (x % i == 0) {
                return false;
            }
        }
        return true;
    }
 }