#include<bits/stdc++.h>
using namespace std;
bool xuebao(int x)
{
	if(x==0||x==1)
	{
		return 0;
	}
    for(int j=2;j<=sqrt(x);j++)
	{
        if(x%j==0)
		{
        	return 0;
		}
	}
    return 1;
}
bool xuebaoHW(int a)
{
    int sum = 0;
    int b = a;
    while(b)
	{
        sum*=10;
        sum+=b%10;
        b/=10;
    }
    if(sum == a)
	{
		return 1;
	} 
    return 0;
}
int main(){
	int a,b;
	cin>>a>>b;
	for(int i=a;i<=b;i++)
	{
		if(!xuebaoWS(i))
		{
			continue;
		}
		if(xuebaoHW(i)&&xuebao(i))
		{
			cout<<i<<endl;
		}
	}
	return 0;
}