#include<bits/stdc++.h>
using namespace std;
int main(){
	int i;
	for(i='A';i<91;i++){
		if((i-65)/10==(i-65)%10) cout<<char(i+1)<<endl;
	} 
return 0;}

/**************************************************************
	Problem: 1973
	User: fzy001
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/