#include <iostream>
#include <cmath>
#include <cstring>
using namespace std;
int n,m;
bool f[100000005];
void run(int m){
	memset(f,1,sizeof(f));
    for (int i=2;i<=sqrt(m);i++){
        if (f[i]){
            for (int j=2;j<=m/i;j++) f[i*j]=false;
        }
    }
}
bool palindromes(int x){
	int s=0,k=x;
	while (x!=0){
		s=s*10+(x%10);x/=10;
	}
	return s==k?1:0;
}
int main(){
    cin>>n>>m;run(m);
    if (n%2==0) n+=1;
    for (int i=n;i<=m;i+=2){
        if (f[i]&&palindromes(i)){
        	cout<<i<<endl;
		}
    }
    return 0;
}

最后一个点TLE,大佬求助Orz