b = map(int, input().split())

lst = []
for a in range(a, b + 1):
    if str(a) == str(a)[::-1]:
        lst.append(a)

for i in lst:
    #剔除偶数
    if i % 2 == 0:
        continue
    #筛选质数
    for j in range(3, int(i ** 0.5) + 1, 2):
        if i % j == 0:
            break #结束内循环
    else:
        print(i)