import sys
import itertools

input = sys.stdin.readline

def main():
    K = int(input())
    N = int(input())

    sieve = [True] * (N+1)

    primes = []

    for i in range(2, N+1):
        if sieve[i]:
            if i >= K: primes.append(i)
            for j in range(i*i, N+1, i):
                sieve[j] = False

    maxv = 0

    for i in range(len(primes)-1, -1, -1):
        vis = [False]*9

        for j in range(i, len(primes)):
            if not vis[primes[j]%9]:
                vis[primes[j]%9] = True
                if maxv < j-i+1:
                    maxv = j-i+1
                    ans = primes[i]
            else:
                break

    print(ans)


if __name__ == '__main__':
    main()