#include <bits/stdc++.h>
using namespace std;
int press(string p);
string guess_sequence(int N) {
char c, p, a[] = {'A', 'B', 'X', 'Y'};
string rtn = "";
if (press("AB") > 0) {
if (press("A") > 0) p = 0;
else p = 1;
}
else {
if (press("X") > 0) p = 2;
else p = 3;
}
rtn += a[p]; a[p] = ' '; sort(a, a + 4);
while (rtn.size() < N - 1) {
int query = press(rtn + a[1] + a[1] + rtn + a[1] + a[2] + rtn + a[1] + a[3] + rtn + a[2]);
if (query == rtn.size() + 2) rtn += a[1];
else if (query == rtn.size() + 1) rtn += a[2];
else rtn += a[3];
}
if (N > 1) {
if (press(rtn + 'A' + rtn + 'B') > rtn.size()) {
if (press(rtn + 'A') > rtn.size()) rtn += 'A';
else rtn += 'B';
}
else {
if (press(rtn + 'X') > rtn.size()) rtn += 'X';
else rtn += 'Y';
}
}
return rtn;
}
