#include <bits/stdc++.h>
using namespace std;
#define pb push_back
int press(string s);
string guess_sequence(int n) {
vector<string> v = {"A", "B", "X", "Y"};
string s;
if(press("AB")) {
if(press("A")) {
s = "A";
swap(v[0], v[3]);
}
else {
s = "B";
swap(v[1], v[3]);
}
}
else {
if(press("X")) {
s = "X";
swap(v[2], v[3]);
}
else {
s = "Y";
}
}
v.pop_back();
for(int i = 2;i <= n;i++) {
string test = s + v[0] + s + v[1];
if(press(test) == i) {
if(press(s+v[0]) == i) {
s += v[0];
continue;
}
s += v[1];
continue;
}
s += v[2];
}
return s;
}
