a,b= input().split()
a = int(a)
b = int(b)
l = []
if a <= 2:
    print(2)
if a%2 == 0:
    a += 1
for i in range(a,b+1,2):
    if i > 10000000:
        break
    else:
        b1 = str(i)
        if b1 == '11':
            l.append(i)
        else:
            if len(b1)%2 != 0:
                j = b1[::-1]
                if j == b1:
                    l.append(i)
for i in l:
    b2 = 2
    while b2<i*0.5:
        if i%b2 == 0:
            break
        b2 += 1
    if (i*0.5)-(b2-1)<1:
       print(i)