def is_prime(n):
    if n <= 1:
        return False
    if n == 2:
        return True
    if n > 2 and n % 2 == 0:
        return False
    for i in range(3,int(n**0.5)+1,2):
        if n % i == 0:
            return False
    return True

def is_palindromes(n):
    return str(n) == str(n)[::-1]

a,b = map(int,input().split())
if a % 2 == 0 and a > 2:
    a += 1
for num in range(a,b+1,2):
    if is_palindromes(num) and is_prime(num):
        print(num)