#include <bits/stdc++.h>
#include "combo.h"
#define taskname ""
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define for0(i, n) for (int i = 0; i < (int)(n); ++i)
#define for1(i, n) for (int i = 1; i <= (int)(n); ++i)
#define ford(i, n) for (int i = (int)(n) - 1; i >= 0; --i)
#define fore(i, a, b) for (int i = (int)(a); i <= (int)(b); ++i)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef complex <ld> cd;
typedef vector <cd> vcd;
typedef vector <int> vi;
template<class T> using v2d = vector <vector <T> >;
template<class T> bool uin(T &a, T b)
{
return a > b ? (a = b, true) : false;
}
template<class T> bool uax(T &a, T b)
{
return a < b ? (a = b, true) : false;
}
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
const int maxN = 1e5 + 10;
int n;
string guess_sequence(int N)
{
int n = N;
string prefix = "";
int p = press(prefix + "AB");
char firstChar;
if (p > 0)
{
p = press(prefix + "A");
if (p > 0)
{
firstChar = 'A';
}
else
{
firstChar = 'B';
}
}
else
{
p = press(prefix + "X");
if (p > 0)
{
firstChar = 'X';
}
else
{
firstChar = 'Y';
}
}
prefix += firstChar;
if (n == 1)
{
return prefix;
}
vector <char> a;
for (char c: {'A', 'B', 'X', 'Y'})
{
if (c != firstChar)
{
a.eb(c);
}
}
fore(i, 2, n - 1)
{
p = press(prefix + a[0] + prefix + a[1] + a[0] + prefix + a[1] + a[1] + prefix + a[1] + a[2]);
if (p == i - 1)
{
prefix += a[2];
}
else if (p == i)
{
prefix += a[0];
}
else
{
prefix += a[1];
}
}
p = press(prefix + a[0]);
if (p == n)
{
prefix += a[0];
}
else
{
p = press(prefix + a[1]);
if (p == n)
{
prefix += a[1];
}
else
{
prefix += a[2];
}
}
return prefix;
}
