a,b=map(int,input().split())
def p(x):
    for s in range(2,int(x**0.5)+1):
        if x%s==0:
            return 0
    return 1

def q(x):
    o=list(str(x))
    for x in range(1,1+len(str(x))//2):
        if o[x-1]!=o[-x]:
            return 0
    return 1
for x in range (a,b+1):
    
    if p(x)==1 and q(x)==1:
        print(x)