#include <iostream>
using namespace std;
int oglindit (int x)
{
int ogl=0;
while (x!=0)
{
ogl=ogl*10+x%10;
x=x/10;
}
return ogl;
}
int prim(int n)
{
int d, nrd=0;
for (d=2; d*d<=n; d++)
if (n%d==0) nrd++;
if (nrd==0) return 1;
else return 0;
}
int main()
{
int a, b, j, ok=0;
cin >> a >> b;
for (j=a; j<=b; j++)
if (prim(oglindit(j))==1 && prim(j)==1)
{
ok=1;
cout << j << " ";
}
if (ok==0) cout << "NU EXISTA";
return 0;
}