MAX = 5000001
dp = [False for _ in range(MAX)]

def make_prime():
    ret = []
    for i in range(2, MAX):
        if dp[i]:
            continue
        ret.append(i)
        for j in range(i, MAX, i):
            dp[j] = True

    return ret

A = [0 for _ in range(10)]
num = [0 for _ in range(10)]

def check(a, move):
    while a != 0:
        num[a % 10] += move
        a //= 10

N = int(input())
tmp = list(map(int, input().split()))
for i in tmp:
    A[i] = 1

primes = make_prime()
ans = -1
last = 0

for i in range(len(primes)):
    check(primes[i], 1)
    for j in range(10):
        if A[j]:
            continue
        while num[j] > 0:
            check(primes[last], -1)
            last += 1

    flag = True
    for j in range(10):
        if not A[j]:
            continue
        if num[j] == 0:
            flag = False

    if i >= last and flag:
        if last != 0:
            K = primes[last - 1] + 1
        else:
            K = 1

        if i != len(primes) - 1:
            L = primes[i + 1] - 1
        else:
            L = 5000000

        ans = max(ans, L - K)

print(ans)