from math import sqrt,ceil
a,b = map(int,input().split())
list2=[]
for i in range(a, b+1):
    if (i % 2 != 0):
        if (str(i) == str(i)[::-1]):
            list2.append(i)
list1=[]
for i in list2:
    a=True
    if(i==2):
        print(i)
    else:
        for j in range(2,ceil(sqrt(i))+1):
            if(i%j==0):
                a=False
                break
        if a:
            print(i)