#include <iostream>
#include <ranges>
#include <algorithm>
#include <vector>
using namespace std;
using ll=long long;

#include <atcoder/all>
using mint=atcoder::modint998244353;

ostream& operator<<(ostream& os,mint& x){
	os<<x.val();
	return os;
}
istream& operator>>(istream& is,mint& x){
	int t;
	is>>t;
	x=t;
	return is;
}

template <typename S,typename T>
ostream& operator<<(ostream& os,const pair<S,T>& p);
template <typename S,typename T>
istream& operator>>(istream& is,pair<S,T>& p);
template <typename T,size_t n>
ostream& operator<<(ostream& os,const array<T,n>& arr);
template <typename T,size_t n>
istream& operator>>(istream& is,array<T,n>& arr);
template <typename T>
ostream& operator<<(ostream& os,const vector<T>& vec);
template <typename T>
istream& operator>>(istream& is,vector<T>& vec);

template <typename S,typename T>
ostream& operator<<(ostream& os,pair<S,T>& p){
	os<<p.first<<" "<<p.second;
	return os;
}
template <typename S,typename T>
istream& operator>>(istream& is,pair<S,T>& p){
	is>>p.first>>p.second;
	return is;
}

template <typename T,size_t n>
ostream& operator<<(ostream& os,array<T,n>& arr){
	for(int i=0;i<n;i++)os<<arr[i]<<(i+1==n?"":" ");
	return os;
}
template <typename T,size_t n>
istream& operator>>(istream& is,array<T,n>& arr){
	for(int i=0;i<n;i++)is>>arr[i];
	return is;
}
template <typename T>
ostream& operator<<(ostream& os,vector<T>& vec){
	for(int i=0;i<vec.size();i++)os<<vec[i]<<(i+1==vec.size()?"":" ");
	return os;
}
template <typename T>
istream& operator>>(istream& is,vector<T>& vec){
	for(int i=0;i<vec.size();i++)is>>vec[i];
	return is;
}

int main(){
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	int b=26;
	vector<vector<int>> graph(b*b);
	for(int i=0;i<b*b;i++)for(int j=0;j<b*b;j++){
		if(i==j)continue;
		if(i%b==j/b)graph[i].push_back(j);
	}
	vector<int> ans;
	vector<bool> seen(b*b);
	auto dfs=[&](auto dfs,int v)->void{
		if(seen[v])return;
		seen[v]=true;
		for(int u:graph[v])dfs(dfs,u);
		ans.push_back(v);
		return;
	};
	dfs(dfs,0);
	ranges::reverse(ans);
	//cout<<ans.size()<<endl;
	for(int x:ans)cout<<((char)('A'+x/b))<<((char)('A'+x%b))<<endl;
}