#include <bits/stdc++.h>
using namespace std;
bool hui(int n)
{
    int a[10],i=1;
    while(n>0){
        a[i]=n%10;
        n/=10;
        i++;
    }
    //if(i%2==0 && n!=11)return false;
    for(int j=1;j<=i;j++)
    {
        if(a[j]!=a[i]) return false;
        i--;
    }
    return true;
}
bool num(int n){
    if((12<=n && n<=99)||(1000<=n && n<=9999)||(100000<=n && n<=999999)||(10000000<=n && 99999999))
        return false;
    else return true;
}
bool zhi(int n)
{
    for(int i=2;i*i<=n;i++)
    {
        if(n%i==0) return false;
    }
    return true;
}
int main(){
    int a,b;
    cin>>a>>b;
    for(int i=a;i<=b;i+=2)
    {
        if(!num(i)) continue;
        else{
            if(hui(i) && zhi(i)) cout<<i<<endl;
        }
    }
    return 0;
}

玄关！！！