#include "combo.h"
#include <bits/stdc++.h>
using namespace std;
string guess_sequence(int N) {
string s = "";
string p = "";
int coins, curCoins;
curCoins = 0;
p = s + "A";
coins = press(p);
if (coins - curCoins == 1) {
s += "A";
} else if (coins - curCoins == 2) {
s += "AB";
} else {
p = s + "X";
coins = press(p);
if (coins - curCoins == 1) {
s += "X";
} else {
s += "Y";
}
}
vector <string> valid;
valid.reserve(3);
if (s[0] != 'A') valid.push_back("A");
if (s[0] != 'B') valid.push_back("B");
if (s[0] != 'X') valid.push_back("X");
if (s[0] != 'Y') valid.push_back("Y");
while((int)s.size() < N) {
p = s + valid[0] + valid[1] + s + valid[0] + valid[2] + s + valid[1];
coins = press(p);
curCoins = s.size();
if (coins - curCoins == 1) {
s += valid[1];
} else if (coins - curCoins == 2) {
s += valid[0];
} else {
s += valid[2];
}
}
return s;
}
