#include <bits/stdc++.h>
using namespace std;
bool isPrime(int x) {
    if (x < 2) return false;
    if (x == 2) return true;
    if (x % 2 == 0) return false;
    for (int i = 3; i * i <= x; i += 2) {
        if (x % i == 0) return false;
    }
    return true;
}
int main() {
    int a, b;
    cin >> a >> b;
    vector<int> ans;
// 枚举回文数长度（1 位到 9 位）
    for (int L = 1; L <= 9; ++L) {
        int halfLen = (L + 1) / 2;
        int start = 1;
        for (int i = 1; i < halfLen; ++i) start *= 10;
        int end = start * 10 - 1;
        for (int i = start; i <= end; ++i) {
            string s = to_string(i);
            string rs = s;
            reverse(rs.begin(), rs.end());
            string pal;
            if (L % 2 == 0)
                pal = s + rs;
            else
                pal = s + rs.substr(1);
            int num = stoi(pal);
            if (num < a || num > b) continue;
            if (isPrime(num)) {
                ans.push_back(num);
            }
        }
    }
    sort(ans.begin(), ans.end());
    ans.erase(unique(ans.begin(), ans.end()), ans.end());
    for (int x : ans) {
        cout << x << '\n';
    }
    return 0;
}