#include <iostream>
#include <cstring>
#define int long long

const int N = 100000001;

using namespace std;

bool is_prime[N];
int p[N];
int a,b;

void pri()
{
	memset(is_prime,1,sizeof(is_prime));
	int np=0;
	for (int i=2;i<=b;i++)
	{
		if(is_prime[i]) p[np++]=i;
		for (int j=0;j<np&&i*p[j]<=b;j++)
		{
			is_prime[i*p[j]]=0;
			if(i%p[j]==0) break;
		}
	}
}

bool judge(int x)
{
	int temp=0;
	int k=x;
	while(k)
	{
		temp=temp*10+k%10;
		k/=10;
	}
	return (temp==x);
}
signed main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);cout.tie(0);
	
	cin >> a >> b;
	pri();
	for (int i=a;i<=b;i++)
	{
		if(is_prime[i]&&judge(i)) cout << i << endl;
	}
}