#include <bits/stdc++.h>
using namespace std;
int main(){
    for(int i = 65;i <= 65+25;i++){
        if(i / 10 == i % 10){
            cout<<(char)i<<endl;
        }
    }
}
/**************************************************************
	Problem: 1973
	User: wngjinming
	Language: C++
	Result: Accepted
	Time:4 ms
	Memory:2072 kb
****************************************************************/