#include <string>
using namespace std;
#define pb push_back
int press(string p);
string guess_sequence(int N) {
string s;
char first = '.';
while (s.size() < N) {
if (s.size() == 1) first = s[0];
if (first != 'A') {
s.pb('A');
if (press(s) == s.size()) continue;
else s.pop_back();
}
if (first != 'B') {
s.pb('B');
if (press(s) == s.size()) continue;
else s.pop_back();
}
if (first != 'X') {
s.pb('X');
if (press(s) == s.size()) continue;
else s.pop_back();
}
if (first != 'Y') {
s.pb('Y');
if (press(s) == s.size()) continue;
else s.pop_back();
}
}
return s;
}
