#include <bits/stdc++.h>
using namespace std;
int press(string p);
vector < char > aux;
string first_char() {
string s = "AB";
int ans = press(s);
if (ans == 2) {
aux = {'B', 'X', 'Y'};
return s;
}
if (ans) {
s = "A";
if (press(s)) {
aux = {'B', 'X', 'Y'};
return s;
}
aux = {'A', 'X', 'Y'};
return "B";
}
s = "X";
if (press(s)) {
aux = {'A', 'B', 'Y'};
return s;
}
aux = {'A', 'B', 'X'};
return "Y";
}
string guess_sequence(int N) {
string s = first_char();
for (int i = (int)s.size() + 1; i <= N - 1; ++i) {
if (i == 2 && s == "A") {
s += aux[1];
if (press(s) == 1) s[1] = aux[2];
continue;
}
string q = s + aux[0] + aux[0] + s + aux[0] + aux[1] + s + aux[0] + aux[2] + s + aux[1];
int ans = press(q);
if (ans == i + 1) s += aux[0];
else if (ans == i) s += aux[1];
else s += aux[2];
}
s += aux[0];
if (press(s) == N) return s;
s[N - 1] = aux[1];
if (press(s) == N) return s;
s[N - 1] = aux[2];
return s;
}
