#include <bits/stdc++.h>
#include "combo.h"
using namespace std;
string guess_sequence(int N) {
int x;
string s;
char ch[] = {'A', 'B', 'X', 'Y'};
if ( press("AB") >= 1) x = press("A") != 1;
else x = 2 + (press("X") < 1);
s += ch[x];
if (N == 1) return s;
swap(ch[x], ch[3]);
for (int i = 1; i < N - 1; ++i) {
x = press(s + ch[0] + ch[0] + s + ch[0] + ch[1] + s + ch[0] + ch[2] + s + ch[1]);
if ( x == i + 2) s += ch[0];
else if ( x == i + 1) s += ch[1];
else s += ch[2];
}
if (press(s + ch[0] + s + ch[1]) == N) {
if (press(s + ch[0]) == N) s += ch[0];
else s += ch[1];
} else s += ch[2];
return s;
}
