#include <iostream>
#include <sstream>
#include <cstdlib>
#include <ctime>
using namespace std;
int gu(int i){
		string s;
		stringstream ss;
		ss<<i;
    	ss>>s;
    	int l,r;
    	l=0;
    	r=s.size()-1;
    	while(l<r){
    		if(s[l]!=s[r])return 0;
    		l++;
    		r--;
		}
		return 1;
}
int su(int i){
	if(i==0||i==1)return 0;
	if(i==2)return 1;
	for(int k=2;k*k<=i;k++)if(i%k==0)return 0;
	return 1;
}
int main(){
	int l,r;
	int a,b;
	cin>>a>>b;
	for(int i=a;i<=b;i++){
	    if(i%2==0)continue;
		if(gu(i))if(su(i))cout<<i<<endl;
	}
}