def isprime(n):
    if n <= 1:
        return False
    elif n == 2:
        return True
    elif n % 2 == 0:
        return False
    
    A = [2, 325, 9375, 28178, 450775, 9780504, 1795265022]
    s = 0
    d = n - 1
    while d % 2 == 0:
        s += 1
        d >>= 1
    
    for a in A:
        if a % n == 0:
            return True
        x = pow(a, d, n)
        if x != 1:
            for t in range(s):
                if x == n - 1:
                    break
                x = x * x % n
            else:
                return False
    return True


n = int(input())
A = list(map(int, input().split()))
B = [0] * n
for i in range(n):
    if A[i] < 10:
        B[i] = 10
    else:
        B[i] = 100
ans = -1
used = [False] * n

memo = set()
def dfs(t, x):
    if t == n:
        global ans
        if x > ans and isprime(x):
            ans = x
        return
    if x in memo:
        return
    memo.add(x)
    for i in range(n):
        if not used[i]:
            used[i] = True
            dfs(t + 1, x * B[i] + A[i])
            used[i] = False
    
dfs(0, 0)
print(ans)