#include<bits/stdc++.h>
#define ll long long
using namespace std;
const ll N=1e8;
const int INF=0x3f3f3f3f;
inline int read(){ll x=0,f=1;char ch=getchar();while (ch<'0'||ch>'9'){if (ch=='-') f=-1;ch=getchar();}while (ch>='0'&&ch<='9'){x=x*10+ch-48;ch=getchar();}return x*f;}
bool vis[N]; 
ll l,r;
void ispri (){
	for(int i=2;i*i<=r;i++){
		if(vis[i]==0){
			for(int j=i+i;j<=r;j+=i){
				vis[j]=1;
			}
		}
	}
}
bool ishw(ll n){
    ll x=n,ans=0;
    while(x!=0){
        ans=ans*10+x%10;
        x/=10;
    }
    if(ans==n)return 1;
    else return 0;
}
int main(){
	cin>>l>>r;
	ispri();
	if(l%2==0)l++;
	for(int i=l;i<=r;i+=2){
		if(vis[i]==0){
			if(ishw(i))
				printf("%d\n", i);
		}
	}
}