def Hash(number):
    while number >= 10:
        number = int(number / 10) + number % 10

    return number


k = int(input())
n = int(input())
numbers = [False for _ in range(n + 1)]
prime = []
max = 0

if k <= 2:
    prime.append(2)

for i in range(3, n + 1, 2):
    numbers[i] = True

for i in range(3, n, 2):
    j = 2
    while i * j <= n:
        numbers[i * j] = False
        j += 1

for i in range(k + 1 - k % 2, n + 1, 2):
    if numbers[i]:
        prime.append(i)

for i in range(0, len(prime) - 1, 1):
    checker = [False for _ in range(10)]
    count = 1
    checker[Hash(prime[i])] = True

    j = 1
    while j < 11 and i + j < len(prime):
        value = Hash(prime[i + j])

        if not checker[value]:
            checker[value] = True
            count += 1
        else:
            break
        j += 1

    if max <= count:
        max = count
        start = prime[i]

print(start)