#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: chenmingyu
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/