#include<iostream>
using namespace std;
bool zhishu(int x)
{
    if(x == 1 || x == 0)
    {
        return 0;
    }
    for(int i = 1; i * i <= x; i++)
    {
        if(x % i == 0)
        {
            return 0;
        }
    }
    return 1;
}
int main()
{
    int n, m;
    cin >> n >> m;
    for(int i = n; i <= m; i++)
    {
        int x = i;
        int num = 0;
        while(x)
        {
            int y = x % 10;
            x /= 10;
            num = num * 10 + y;
        }
        if(zhishu(i) && zhishu(num))
        {
            cout << i << endl;
        }
    }
    return 0;
}