#include<iostream>

using namespace std;

bool is_prime(int n){
	if(n == 0 || n == 1 || n % 2 == 0) return 0;
	if(n == 2 || n == 3) return 1;
	for(int i = 3;i * i <= n;i += 2){
		if(n % i == 0) return 0;
	}
	return 1;
}

int rev(int n){
	int m = 0;
	while(n){
		m = m * 10 + n % 10;
		n /= 10;
	}
	return m;
}

bool is_pal(int n){
	return n == rev(n);
}

int main(){
	
	int l,r;
	cin >> l >> r;
	if(l % 2 == 0) l++;
	for(int i = l;i <= r;i += 2){
		if(is_pal(i)){
			if(is_prime(i)){
				cout << i << endl;
			}
		}
	}
	
	return 0;
}

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