import numpy as np
K = int(input())
N = int(input())

p_list = []
for i in range(2, N+1):
    flg = 0
    for p in p_list:
        if np.sqrt(i) < p:
            break
        if i % p == 0:
            flg = 1
            break
    if flg == 0:
        p_list.append(i)

k_list = [p for p in p_list if p >= K]

hash_list = [0] * len(k_list)
for i, k in enumerate(k_list):
    if k < 10:
        hash = k % 10
    else:
        while k >= 10:
            hash = 0
            while k >= 10:
                hash += k % 10
                k //= 10
            hash += k % 10
            k = hash
    hash_list[i] = hash

result = 0
max_size = 0
j = 0
for i in range(len(hash_list)):
    while hash_list[i] in hash_list[j:i]:
        j += 1
    if max_size <= len(hash_list[j:i+1]):
        max_size = len(hash_list[j:i+1])
        result = j

print (k_list[result])