#include<bits/stdc++.h>
using namespace std;
long long a,b,g,n,h;
bool check(long long x)
{
	if(x == 2) return 1;
	for(long long i = 2; i <= sqrt(x); i++) 
		if(x % i == 0) return false;
	return true;
} 
bool hws(long long num) {
    int temp=num,ans=0;
    while (temp!=0) {
        ans=ans*10+temp%10;
        temp/=10;
    }
    if (ans==num)
        return true;
    else
        return false;
}
int main(){
	cin>>a>>b;
	if(a%2==0)a++;
	for(long long i=a;i<=b;i+=2)
	{
		if(b>=9999999) b=9999999;
		if(check(i)&&  hws(i)) cout<<i<<endl;
	}
	return 0;
}

66分，求调。