#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <cassert>
using namespace std;
inline bool operator == (string &a, string &b)
{
if(a.size() != b.size()) return 0;
for(int i = 0 ; i < a.size() ; ++i)
{
if(a[i] != b[i])
{
return 0;
}
}
return 1;
}
int press(string p);
string guess_sequence(int N)
{
string res = "";
string letters = "";
if (press("A")) res.append("A");
else if (press("B")) res.append("B");
else if (press("X")) res.append("X");
else res.append("Y");
for(string s : {"A", "B", "X", "Y"})
{
if(s == res) continue;
letters.append(s);
}
for(int i = 1 ; i < N - 1 ; ++i)
{
int ans = press(res + letters[0] +
res + letters[1] + letters[0] +
res + letters[1] + letters[1] +
res + letters[1] + letters[2]);
if(ans == i + 1) ans += letters[0];
else if(ans == i + 2) ans += letters[1];
else ans += letters[2];
}
if (press(res + "A") == N) res.append("A");
else if (press(res + "B") == N) res.append("B");
else if (press(res + "X") == N) res.append("X");
else res.append("Y");
return res;
}
