#include <bits/stdc++.h>
#include "combo.h"
#define For(i, a, n) for(int i = a; i<n; ++i)
using namespace std;
string guess_sequence(int N){
string s = "";
vector<char> v = {'A', 'B', 'X', 'Y'};
int v1 = press("AB");
if(!v1){
int v2 = press("X");
s += v2 ? 'X' : 'Y';
} else {
int v2 = press("A");
s += v2 ? 'A' : 'B';
}
For(i, 0, 4) { if(v[i] == s[0]){ v.erase(v.begin()+i, v.begin()+i+1); break;}}
For(i, 1, N-1){
string a1 = s + v[0];
string a2 = s + v[1];
string t = a1;
for(char c: v){
t += a2 + c;
}
int v2 = press(t);
if(v2 == s.size()) s += v[2];
else if(v2 == s.size()+2) s += v[1];
else s += v[0];
}
if(N==1) return s;
string t = s + v[0] + s + v[1];
int v2 = press(t);
if(v2==N){
int v3 = press(s+v[0]);
if(v3==N) s += v[0];
else s += v[1];
}
else s+=v[2];
return s;
}
