#include "combo.h"
#include <algorithm>
#include <vector>
using namespace std;
#define all(v) (v).begin(), (v).end()
vector<char> chr = {'A', 'B', 'X', 'Y'};
string guess_sequence(int N) {
string S;
if (press("AB") == 0) {
if (press("X"))
S += 'X';
else
S += 'Y';
} else {
if (press("A"))
S += 'A';
else
S += 'B';
}
chr.erase(remove(all(chr), S[0]), chr.end());
while ((int)S.size() <= N - 2) {
string p;
for (int i = 0; i < 3; i++) {
p += S;
p += chr[0];
p += chr[i];
}
p += S;
p += chr[1];
int coin = press(p);
if (coin == S.size() + 2) {
S += chr[0];
} else if (coin == S.size() + 1) {
S += chr[1];
} else {
S += chr[2];
}
}
if (S.size() < N) {
for (int i = 0; i < 2; i++) {
if (press(S + chr[i]) == N) {
S.push_back(chr[i]);
break;
}
}
if (S.size() != N)
S += chr[2];
}
return S;
}