#include<bits/stdc++.h>
using namespace std;
//#include "combo.h"
// define
//bool M1;
//#define execute cerr << " Time: " << fixed << setprecision(6) << (1.0 * clock() / CLOCKS_PER_SEC) << "s\n";
//#define memory cerr << abs(&M2 - &M1)/1024.0/1024 << " MB" << "\n"
#define ll long long
#define ii pair <int , int>
#define iii pair <int , ii>
#define se second
#define fi first
#define all(v) (v).begin() , (v).end()
#define Unique(v) sort(all(v)) , v.resize(unique(all(v)) - v.begin())
#define bit(x,i) (((x) >> (i)) & 1LL)
#define flip(x,i) ((x) ^ (1LL << (i)))
#define ms(d,x) memset(d , x , sizeof(d))
#define exist __exist
#define ends __ends
#define visit visited
#define left __left
#define right __right
#define prev __prev
#define next __next
#define sitingfake 1
#define orz 1
//constant
const long long mod = 1e9 + 7;
const long long linf = 4557430888798830399LL;
const long long nlinf = -4485090715960753727LL;
const int inf = 1061109567;
const int ninf = -1044266559;
const int dx[] = {0 , -1 , 0 , 1};
const int dy[] = {-1 , 0 , 1 , 0};
template<typename T> bool maximize(T &a, const T &b)
{
if(a < b) {a = b; return 1;}
return 0;
}
template<typename T> bool minimize(T &a, const T &b)
{
if(a > b) {a = b; return 1;}
return 0;
}
void Plus(ll & a ,ll b)
{
b %= mod;
a += b;
if(a < 0) a += mod;
a %= mod;
return;
}
void Mul(ll & a, ll b)
{
(a *= (b % mod)) %= mod;
return;
}
//code
//const string base = "AYXXBXYBXXYYXXBBB";
//
//int press(string p)
//{
// int ans = 0;
// for(int i = 0; i < p.size(); i++)
// {
// int it = 0;
// while(it < base.size() && p[i + it] == base[it]) ++it;
// ans = max(ans , it);
// }
// cout << p.size() << " " << p << " " << ans << endl;
// return ans;
//}
string c[] = {"A" , "B" , "X" , "Y"};
string guess_sequence(int N)
{
string s = "";
int tmp = press(c[0] + c[1]);
if(tmp == 0)
{
tmp = press(c[2]);
if(tmp) s = s + c[2];
else s = s + c[3];
}
else
{
tmp = press(c[1]);
if(tmp)s = s + c[1];
else s = s + c[0];
}
vector <string> p;
for(int i = 0; i < 4; i++)
{
if(c[i] != s) p.push_back(c[i]);
}
for(int i = 1; i < N - 1; i++)
{
int d = press(s + p[0] + p[0] + s + p[0] + p[1] + s + p[0] + p[2] + s + p[1]);
if(d == s.size()) s = s + p[2];
else if(d - 1 == s.size()) s = s + p[1];
else s = s + p[0];
}
tmp = press(s + p[0] + s + p[1]);
if(tmp == N)
{
tmp = press(s + p[0]);
if(tmp == N) s = s + p[0];
else s = s + p[1];
}
else s = s + p[2];
return s;
}
//void solve(void)
//{
// cout << guess_sequence(base.size());
//}
///**
//**/
//bool M2;
//signed main()
//{
// ios_base::sync_with_stdio(0);
// cin.tie(0);
// cout.tie(0);
//
// #define task ""
//
// if(fopen(task".inp","r"))
// {
// freopen(task".inp","r",stdin);
// freopen(task".out","w",stdout);
// }
//
// int tc = 1;
// cin >> tc;
// while(tc--) solve();
//
// execute;
// memory;
//}
