#include<bits/stdc++.h>

using namespace std;
const int N = 1e8 + 10;
int primes[N], cnt;
bool st[N];
void get_primes(int n) {
    for (int i = 2; i <= n; i++) {
        if (!st[i]) primes[cnt++] = i;
        for (int j = 0; primes[j] <= n / i; j++) {
            st[primes[j] * i] = true;
            if (i % primes[j] == 0) break;
        }
    }
}
bool isHWS(int num) {
    int t = num, ans = 0;
    while (t) {
        ans = ans * 10 + t % 10;
        t /= 10;
    }
    return ans == num;
}
int main() {
    int a, b;
    cin >> a >> b;
    if (b >= 1e7) b = 1e7;
    get_primes(b);
    for (int i = a; i <= b; i++)
        if (!st[i] && isHWS(i))
            cout << i << endl;
    return 0;
}