#include <bits/stdc++.h>
using namespace std;
int main(void){
    vector<int>v(26,0);
    v[0]++,v[25]++;
    cout<<"ZA"<<endl<<"AA"<<endl;
    int now=0;
    while(1){
        if(v[now]==26)break;
        cout<<(char)('A'+now)<<(char)('A'+v[now])<<endl;
        int tmp=v[now];
        v[now]++;
        now=tmp;
    }
    return 0;
}