#include <bits/stdc++.h>
using namespace std;
int a[100000000];
bool huiwen(int x) {
    int i = 0;
    while (x) {
        a[i] = x%10;
        x /= 10;
        i++;
    }
    int k = i;
    if (i != 2 && i%2 == 0) return false;
    for (int j = 0; j < k/2; j++) {
        if (a[j] != a[i-1]) return false;
        i--;
    }
    return true;
}
bool check(int x) {
    for (int i = 3; i*(i-1) < x; i++) {
        if (x%i == 0) return false;
    }
    return true;
}
int main() {
    long long n,m;
    cin >> n >> m;
    for (int i = n; i <= m; i++) {
        if (i != 2 && i%2 == 0) continue;
        if (i == 100000000) break;
        if (huiwen(i) && check(i)) cout << i << endl;
    }
}