#include<bits/stdc++.h>
#define l long
#define ll long long
#define fl float
#define dou double
#define ld long double
#define st string
#define str struct

using namespace std;

int main(){
	ll a,b;
	ll d = 1;
	scanf("%d",&a);
	scanf("%d",&b);
	for(ll i = a;i <= b;i++){
		stringstream ss;
		ss << i;
		string s,c;
		ss >> s;
		
		if(s.size() == 2 && a <= 11 && b >= 11){
			if(d == 1){
				cout << 11 << endl;
				d = 0;
			}
			else if(d == 0){
				continue;
			}
		}
		
		else if(s.size() != 2){
			if(s.size() % 2 == 0){
				continue;
			}
			else{
				for(ll k = s.size() - 1;k >= 0;k--){
					s[k] = s[k];
					c += s[k];
				}
				if(s == c){
					bool flag = 1;
					for(ll j = 2;j <= sqrt(i);j++){
						if(i % j == 0){
							flag = 0;
							continue;
						}
						else
						continue;
					}
					if(flag == 1){
						printf("%d\n",i);
						//cout << endl;
					}
					else 
					continue;
				}				
			}
		}
		else{
			continue;
		}
	}
}

本蒟蒻第一次发贴不太会请大佬指教和谅解！