#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int press(string p);
string guess_sequence(int n) {
char fc;
{
int c = press("AB");
if (c) {
int d = press("A");
if (d) fc = 'A';
else fc = 'B';
} else {
int d = press("X");
if (d) fc = 'X';
else fc = 'Y';
}
}
string res; res.reserve(n);
res += fc;
vector<char> rm = {'A', 'B', 'X', 'Y'};
erase(rm, fc);
while ((int)res.length() < n-1) {
int c = press(res+rm[1] + res+rm[0]+rm[0] + res+rm[0]+rm[1] + res+rm[0]+rm[2]);
if (c == (int)res.length()) res += rm[2];
if (c == (int)res.length()+1) res += rm[1];
if (c == (int)res.length()+2) res += rm[0];
}
if (n > 1) {
int c = press(res+rm[0]);
if (c == (int)res.length()+1) res += rm[0];
else {
int d = press(res+rm[1]);
if (d == (int)res.length()+1) res += rm[1];
else res += rm[2];
}
}
return res;
}
