#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) {
string ans = "A";
vector <string> c = {"A", "B", "X", "Y"};
int x = press("AB");
if (x >= 1) {
ans = (press("A") ? "A" : "B");
} else {
ans = (press("X") ? "X" : "Y");
}
vector <string> all;
for (auto s : c) {
if (s == ans) continue;
all.pb(s);
}
while ((int)ans.size() != n) {
if ((int)ans.size() <= n - 2) {
string t = ans + all[0] + ans + all[1] + all[0] + ans + all[1] + all[1] + ans + all[1] + all[2];
x = press(t);
if (x == (int)ans.size()) ans += all[2];
else if (x == (int)ans.size() + 1) ans += all[0];
else ans += all[1];
} else {
string t = ans + all[0] + ans + all[1];
x = press(t);
if (x == (int)ans.size()) ans += all[2];
else {
x = press(ans + all[0]);
if (x == (int)ans.size()) ans += all[1];
else ans += all[0];
}
}
}
return ans;
}
