#!/usr/bin/env python3
from itertools import dropwhile


def sqrt_floor(n):
    l = 5 * n
    r = 5
    sqrt = 0
    while l > r:
        sqrt += 1
        l = l - r
        r += 10
    return sqrt


def sieve_of_eratosthenes(max):
    is_prime = [True] * (max + 1)
    is_prime[0] = False
    is_prime[1] = False
    for i in range(2, sqrt_floor(max) + 1):
        if not is_prime[i]:
            continue
        for j in range(i * i, max + 1, i):
            is_prime[j] = False
    return filter(lambda x: is_prime[x], range(max + 1))


def digital_root(n):
    if n == 0:
        return 0
    if n % 9 == 0:
        return 9
    return n % 9


def length(digitals, start_index):
    appeared = []
    count = 0
    for i in digitals[start_index:]:
        if i in appeared:
            break
        appeared.append(i)
        count += 1
    return count

K = int(input())
N = int(input())
primes = tuple(dropwhile(lambda x: x < K, sieve_of_eratosthenes(N)))
digitals = tuple(map(digital_root, primes))
maxlength = 0
index = 0
for i in range(len(digitals)):
    tmp = length(digitals, i)
    if tmp >= maxlength:
        maxlength = tmp
        index = i
print(primes[index])