#include <bits/stdc++.h>
using namespace std;
int press(string p);
// cout << p << endl;
// int x;
// cin >> x;
// return x;
//}
string guess_sequence(int N) {
string p = "AB";
string ans = "";
int coins = press(p);
char v0;
if (coins != 0) {
p = "A";
if (press(p)) {
v0 = 'A';
ans = "A";
}
else {
v0 = 'B';
ans = "B";
}
}
else {
p = "X";
coins = press(p);
if (coins) {
ans += "X";
v0 = 'X';
}
else {
ans += "Y";
v0 = 'Y';
}
}
if (N == 1) {
return ans;
}
vector<char> e = {'A', 'B', 'X', 'Y'};
e.erase(find(e.begin(), e.end(), v0));
while (ans.size() < N - 1) {
p.clear();
for (int i = 0; i < 3; i++) {
p += ans + e[0] + e[i];
}
p += ans + e[1];
int coins = press(p);
if (coins == 3) {
ans += e[0];
}
else if (coins == 2) {
ans += e[1];
}
else {
ans += e[2];
}
}
p = ans + e[0];
if (press(ans + e[0])) {
return (ans + e[0]);
}
else if (press(ans + e[1])) {
return (ans + e[1]);
}
return (ans + e[2]);
}
//int main() {
// cout << guess_sequence(2) << endl;
//}//yaa, yab, yba, ybb,
