#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: yangjunwen
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/