#include<bits/stdc++.h>
using namespace std;
int main(){
	int b=1000,c,d,e,f;
    while(b<10000){
    	c=b%10;
    	d=b/10%10;
    	e=b/100%10;
    	f=b/1000;
    	if(c==f&&d==e){
    		cout<<b<<endl;
    	}
    	b++;
    }
}
/**************************************************************
	Problem: 1447
	User: lvrenxiang
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/