#!/usr/bin/env python3
import sys
input = sys.stdin.readline

# O(nloglogn)
def primes(k, n):
    is_prime = [True] * (n + 1)
    is_prime[0] = False
    is_prime[1] = False
    for i in range(2, int(n**0.5) + 1):
        if not is_prime[i]:
            continue
        for j in range(i * 2, n + 1, i):
            is_prime[j] = False
    return [i for i in range(k, n + 1) if is_prime[i]]

def hash(n):
    while n >= 10:
        t = 0
        while n > 0:
            t += n % 10
            n //= 10
        n = t
    return n

k = int(input())
n = int(input())

p = primes(k, n)
d = []
for item in p:
    digits = sum([int(dgt) for dgt in str(item)])
    d.append(hash(item))
max_length = 0
ans = 0
for i, item in enumerate(d):
    cnt = [0] * 10
    cnt[item] += 1
    for j in range(i + 1, len(d) + 1):
        if j == len(d) or cnt[d[j]] > 0:
            break
        else:
            cnt[d[j]] += 1
    if j - i >= max_length:
        ans = i
        max_length = j - i
print(p[ans])