import math
a,b = map(int,input().split())

if(b > 100000000): b = 100000000
m = 1
if(a % 2 ==0):
    a += 1
elif(a % 2 != 0):
    m = 2
for i in range(a,b+1,m):
    x = str(i)
    if(x == x[::-1]):
        flag = 0
        for n in range(2,int(math.sqrt(i))+1):
            if(i % n == 0):
                flag = 1
        if(flag == 0):
            print(i)