a = int(input())
b = int(input())

for i in range(a, b + 1):
    count = 0
    for j in range(2, i):
        if i % j == 0:
            count += 1
    if count == 0:
        s1 = str(i)
        s2 = s1[::-1]
        if s1 == s2:
            print(i)