#include <bits/stdc++.h>
#include "combo.h"
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define all(X) X.begin(), X.end()
#define allr(X) X.rbegin(), X.rend()
#define pb push_back
#define endl '\n'
using namespace std;
using namespace __gnu_pbds;
int press(string p);
string guess_sequence(int n){
string res = "";
ll cnt = 0;
vector<char>ch = {'A', 'B', 'X', 'Y'};
for(ll i = 0; i < 4; i++){
res = ch[i];
if(press(res)){
ch.erase(ch.begin() + i);
break;
}
}
for(ll i = 0; i < n; i++){
for(ll j = 0; j < 3; j ++){
string temp = res + ch[j];
if(press(temp) > cnt){
res = temp;
cnt++;
break;
}
}
}
return res;
}
