#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: admin
	Language: C++
	Result: Accepted
	Time:5 ms
	Memory:2072 kb
****************************************************************/