#include "combo.h"
#include <bits/stdc++.h>
using namespace std;
string guess_sequence(int N) {
string p = "";
int j;
vector<char> letters = {'A', 'B', 'X', 'Y'};
for (int i = 0; i < 4; i++) {
p = string(1, letters[i]);
int coins = press(p);
if (coins == 1) {
j = i;
break;
}
}
letters.erase(letters.begin() + j);
string S = p;
for (int l = 1; l < N; l++) {
for (int k = 0; k < letters.size(); k++) {
S += letters[k];
int coins = press(S);
if (coins == S.size()) {
break;
}
S.pop_back();
}
}
return S;
}
