/*
#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx2,fma,bmi,bmi2,sse4.2,popcnt,lzcnt")
*/
#include <bits/stdc++.h>
#include "combo.h"
#define taskname ""
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define ll long long
#define ld long double
#define pb push_back
#define ff first
#define ss second
#define pii pair<int, int>
#define vi vector<int>
#define vii vector<pii>
using namespace std;
const int mxN = 2e5 + 5;
const int mod = 1e9 + 7;
const ll oo = 1e18;
char c[] = {'A', 'B', 'X', 'Y'};
string guess_sequence(int N) {
int n = N;
int cur = press("AB");
string s;
if(cur) {
cur = press("A");
if(cur) s = "A";
else s = "B";
}
else {
cur = press("X");
if(cur) s = "X";
else s = "Y";
}
if(n == 1) {
return s;
}
vector<char> sadge;
for(int i = 0; i < 4; ++i)
if(c[i] != s[0])
sadge.emplace_back(c[i]);
for(int i = (int)s.size(); i < n - 1; ++i) {
string tmp;
tmp += s;
tmp.pb(sadge[0]);
tmp.pb(sadge[0]);
tmp += s;
tmp.pb(sadge[0]);
tmp.pb(sadge[1]);
tmp += s;
tmp.pb(sadge[0]);
tmp.pb(sadge[2]);
tmp += s;
tmp.pb(sadge[1]);
int cur = press(tmp);
if(cur == i) s.pb(sadge[2]);
else if(cur - 1 == i) s.pb(sadge[1]);
else s.pb(sadge[0]);
}
string tmp = s;
tmp.pb(sadge[0]);
if(n == press(tmp)) {
s.pb(sadge[0]);
return s;
}
tmp.pop_back();
tmp.pb(sadge[1]);
if(n == press(tmp)) {
s.pb(sadge[1]);
return s;
}
s.pb(sadge[2]);
return s;
}
