def Eratosthenes(N): #N以下の素数のリストを返す
    N+=1
    is_prime_list = [True]*N
    is_prime_list[0], is_prime_list[1] = False, False #リストが必要なときはこの2行を有効化
    for j in range(4,N,2): is_prime_list[j] = False
    m = int(N**0.5)+1
    for i in range(3,m,2):
        if is_prime_list[i]:
            is_prime_list[i*i::2*i]=[False]*((N-i*i-1)//(2*i)+1)
    #return [2] + [i for i in range(3,N,2) if is_prime_list[i]]
    return is_prime_list


res = [0]*10
n = int(input())
*a, = map(int,input().split())
for ai in a:
    res[ai] += 1

N = 5*10**6+1
ans = -1
lst = Eratosthenes(N)
used = [0]*10
r = 1
for l in range(1,N):
    if r < l:
        for i in str(r+1):
            used[int(i)] += 1
        r += 1
    while r < N:
        if lst[r+1]==1:
            flag = 1
            for i in str(r+1):
                if res[int(i)]==0: flag = 0
            if flag:
                for i in str(r+1):
                    used[int(i)] += 1
            else:
                break
        r += 1
    for i in range(10):
        if (res[i] and used[i]==0) or (res[i]==0 and used[i]): break
    else:
        ans = max(ans,r-l)
        #print(l,r,used)
    #if l <= 20: print(l,r,used)
    if lst[l]:
        for i in str(l):
            used[int(i)] -= 1

print(ans)