#include<bits/stdc++.h>
using namespace std;
bool prime(int n)
{
    if (n < 2) return 0;
    for(int i = 2;i*i<=n;++i)
    {
        if(n%i==0) return 0;
    }
    return 1;
}

int main()
{
    int a,b;
    cin>>a>>b;
    for (int i = a;i <= b;++i)
    {
        int j = 0;
        while(i!=0)
        {
            j = j*10+i%10;
            i=i/10;
        }
        if(prime(i) && prime(j))
        {
            cout<<i<<endl;
        }
    }
    return 0;
}