// #pragma GCC optimize("Ofast,unroll-loops")
// #pragma GCC target("avx,avx2,sse,sse2")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include "combo.h"
using namespace __gnu_pbds;
using namespace std;
#define ll long long
#define ld long double
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define pb push_back
#define eb emplace_back
#define F first
#define S second
#define mp make_pair
#define random mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
template <typename T> using oset = tree <pair <T, T>, null_type, less <pair <T, T>>, rb_tree_tag, tree_order_statistics_node_update>;
template <typename Container>
void Print(Container& container, int starting) {
auto Start = container.begin() + starting, End = container.end();
while (Start != End) cout << *(Start++) << " ";
cout << '\n';
}
template <typename T>
void print(T&& t) {cout << t << '\n';}
template <typename T, typename... Args>
void print(T&& t, Args&&... args) {
cout << t << " ";
print(forward<Args>(args)...);
}
string guess_sequence(int n) {
char first = '.';
string s = "";
for (int i = 1; i <= n; ++i) {
for (char c : {'A', 'B', 'X', 'Y'}) {
if (first == c) continue;
if (first == '.') first = c;
string t = s + c;
if (press(t) == i) {
s = t;
break;
}
}
}
return s;
}
