a,b=map(int,input().split())
def zhishu(x):
    for i in range(2,int(x**0.5+1)):
        if x%i==0:
            return 0
    return 1
def huiwen(y):
    t=len(str(y))
    s=list(str(y))
    for i in range(int(t/2)):
        if s[i]!=s[t-i-1]:
            return 0
    return 1
for j in range(a,b+1):
    if zhishu(j) and huiwen(j):
            print(j)