#include<bits/stdc++.h>
using namespace std;
int main(){
	int i;
	for(i=1000;i<=9999;i++){
		if(i%10==i/1000&&i/10%10==i/100%10){
			cout<<i<<endl;
		}
	}
	return 0;
}

/**************************************************************
	Problem: 1447
	User: tangkaixuan
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/