#include<bits/stdc++.h>
using namespace  std;
int a,b; 
int  main( ) 
{
    cin>>a>>b;
    for (int i=a;i<=b;i++)
    {
        int x=i,y=i/10+i%10*10,ok1=1,ok2=1;
        for (int j=2;j*j<=x;j++)
            if (x%j==0)
                ok1=0;
        for (int j=2;j*j<=y;j++)
            if (y%j==0)
                ok2=0;
        if (ok1==1 && ok2==1)
            cout<<i<<endl;
    }
    return 0;   
}