#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N = 1e7 + 7;
bool huiwen(int x){
    int ans = 0;
    for(int i = x; i > 0; i /= 10){
        ans = ans * 10 + i % 10;
    }
    return ans == x;
}
int l, r;
bool a[N];
signed main(){
    cin >> l >> r;
    a[1] = 1;
    for(int i = 2; i * i <= r; i ++){
        if(a[i] == 0){
            for(int j = i + i; j <= r; j += i)
                a[j] = 1;
        }
    }
    for(int i = l; i <= r; i ++){
        if(huiwen(i)  && a[i] == 0) cout << i << "\n";
    }
    return 0;
}

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