# #S = list(map(int, input().split()))
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 = list()
for k in k_list:
    if k < 10:
        ans = k % 10
    else:
        while k >= 10:
            ans = 0
            while k >= 10:
                ans += k % 10
                k //= 10
            ans += k % 10
            k = ans
    hash_list.append(ans)

result = 0
max_size = 0
result_list = []
for i, j in enumerate(hash_list):
    while True:
        if j in result_list:
            result_list.pop(0)
            continue
        else:
            result_list.append(j)
            break
    if max_size <= len(result_list):
        max_size = len(result_list)
        result = i - (len(result_list) - 1)

print (k_list[result])