import sys

input = sys.stdin.readline


def main():
    MAXN = 5000000
    N = int(input())

    if N == 10:
        print(MAXN-1)
        return

    *A, = map(int, input().split())
    mask = 0
    for i in A:
        mask |= 1 << i

    sieve = [True]*(MAXN+1)
    primes = [(0, -1)]

    def msk(x):
        ans = 0
        while x > 0:
            ans |= 1 << (x % 10)
            x //= 10
        return ans

    for i in range(2, MAXN+1):
        if sieve[i]:
            primes.append((i, msk(i)))
            for j in range(i*i, MAXN+1, i):
                sieve[j] = False

    primes.append((MAXN+1, -1))

    ans = -1
    k = l = 1
    num_mask = 0

    for l in range(1, len(primes)-1):
        num_mask |= primes[l][1]
        if num_mask == mask:
            ans = max(ans, primes[l+1][0] - primes[k-1][0] - 2)
        elif (num_mask | mask) != mask:
            k = l + 1
            num_mask = 0

    print(ans)


if __name__ == '__main__':
    main()