#include<bits/stdc++.h>
using namespace std;
int x,y;
bool pdss(int a){
	if(a%2==0)
		return 0;
	for(int i=3;i*i<=a;i+=2)
		if(a%i==0)
			return 0;
	return 1;
}
int main(){
	cin>>x>>y;
	if(x%2==0) x++;
	if(y%2==0) y--;
	for(int i=x;i<=y;i+=2)
	{
		if(pdss(i) == 1)
		{
			if(i/10==0)
				cout<<i<<"\n";
			else
			{
				int s=i,t=0,g[10];
				while(s!=0)
				{
					t++;
					g[t]=s%10;
					s/=10;
				}
				if(t%2==0)
				{
					int k;
					for(int j=1,j<=t/2,j++;k=t;k>=t/2+1,k--)
					{
						if(g[j]!=g[k])
							break;
					}
					cout<<i<<"\n";
				}
				else if(t%2!=0)
				{
					for(int j=1,j<=t/2,j++;k=t;k>t/2+1,k--)
					{
						if(g[j]!=g[k])
							break;
					}
					cout<<i<<"\n";
				}
			}
			
		}
	}
	return 0;
}