#include <bits/stdc++.h>
using namespace std;
bool z(long long a)
{
  for (int i = 2; i * i <= a; i++)
  {
    if (a % i == 0)
    {
      return false;
    }
  }
  return true;
}
bool c(int i)
{
  if(i<0)
    return 0;
  long long h = 0, k = i;
  while (k > 0)
  {
    h = h * 10 + k % 10;
    k /= 10;
  }
  if(h == i && h % 2 == 1)
  {
    if (z(i))
      return 1;
  }
  return 0;
}
int main()
{
  long long m, n;
  cin >> n >> m;
  for (long long i = n; i <= m; i++)
  {
    if(c(i))
      cout << i << endl;
  }
  return 0;
}