#include "combo.h"
#include <bits/stdc++.h>
using namespace std;
string guess_sequence(int N) {
char a, b, x, y;
a='A', b='B', x='X', y='Y';
if (press("AB")){
if (press("A"));
else swap(a, b);
}else{
if (press("X")) swap(a, x);
else swap(a, y);
}
string ans(1, a);
while ((int)ans.size()+2<=N){
string guess=ans+x+ans+y+b+ans+y+x+ans+y+y;
int t=press(guess)-(int)ans.size();
if (t==0) ans.push_back(b);
else if (t==1) ans.push_back(x);
else ans.push_back(y);
}
if ((int)ans.size()!=N){
if (press(ans+b)==N) ans.push_back(b);
else if (press(ans+x)==N) ans.push_back(x);
else ans.push_back(y);
}
return ans;
}
