import sys
from itertools import permutations

def is_prime(n):
    if n <= 1:
        return False
    elif n <= 3:
        return True
    elif n % 2 == 0:
        return False
    d = n - 1
    s = 0
    while d % 2 == 0:
        d //= 2
        s += 1
    for a in [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37]:
        if a >= n:
            continue
        x = pow(a, d, n)
        if x == 1 or x == n - 1:
            continue
        for _ in range(s - 1):
            x = pow(x, 2, n)
            if x == n - 1:
                break
        else:
            return False
    return True

def main():
    input = sys.stdin.read().split()
    n = int(input[0])
    a = input[1:n+1]
    cards = list(map(str, a))
    unique_numbers = set()
    for p in permutations(cards):
        num_str = ''.join(p)
        unique_numbers.add(num_str)
    candidates = []
    for s in unique_numbers:
        candidates.append(int(s))
    candidates.sort(reverse=True)
    for num in candidates:
        if is_prime(num):
            print(num)
            return
    print(-1)

if __name__ == "__main__":
    main()