#include <bits/stdc++.h>
using namespace std;
int press(string p);
string guess_sequence(int n) {
string s;
if (press("AB") >= 1) {
s = (press("A") >= 1) ? "A" : "B";
} else {
s = (press("X") >= 1) ? "X" : "Y";
}
string all = "ABXY";
while ((int)s.size() < n) {
string rest;
for (char ch : all) if (ch != s[0]) rest += ch;
char a = rest[0], b = rest[1], c = rest[2];
int k = (int)s.size();
if (press(s + a) == k + 1) s.push_back(a);
else if (press(s + b) == k + 1) s.push_back(b);
else s.push_back(c);
}
return s;
}
