import bisect
def sieve(n):
    is_prime = [True for _ in range(n+1)]
    is_prime[0] = False
    is_prime[1] = False

    for i in range(2, n+1):
        if not is_prime[i]:
            continue
        for j in range(i*2, n+1, i):
            is_prime[j] = False
    table = [ i-1 for i in range(1, n+1) if is_prime[i-1]] # 素数のリスト
    return table

def digsum(n):
    res = 0
    while n > 0:
        res += n%10
        n //= 10
    
    return res

K = int(input())
N = int(input())

prime = sieve(N+1)
idx = bisect.bisect_left(prime, K)

hash = []
for i in range(idx,len(prime)):
    n = digsum(prime[i])
    while len(str(n)) > 1:
        n = digsum(n)
    hash.append(n)

length = len(hash)
r, ans, max_len = 0, 0, 0
for l in range(length):
    while r < length and len(hash[l:r]) == len(set(hash[l:r])):
        r += 1
    if len(set(hash[l:r])) >= max_len:
        ans = prime[idx+l]
        max_len = len(set(hash[l:r]))
    if l == r:
        r += 1
print(ans)