#include "combo.h"
#include <bits/stdc++.h>
using namespace std;
std::string guess_sequence(int N) {
char fir;
string ans;
bool alsob=0;
long long ab=press("AB");
if(ab==0){
if(press("X")==1)fir='X';
else fir ='Y';
}
else if(ab==1){
if(press("A")==1)fir = 'A';
else fir = 'B';
}
else {
fir = 'A';
alsob=1;
}
ans.push_back(fir);
vector<char> pos;
if(fir!='A')pos.push_back('A');
if(fir!='B')pos.push_back('B');
if(fir!='X')pos.push_back('X');
if(fir!='Y')pos.push_back('Y');
if(alsob)ans.push_back('B');
while(ans.size()!=N){
string pre;
pre+=ans;
pre.push_back(pos[0]);
pre+=ans;
pre.push_back(pos[1]);
long long cn = press(pre);
if(cn==ans.size())ans.push_back(pos[2]);
else {
if(press(ans+pos[0])==ans.size()){
ans.push_back(pos[1]);
}
else ans.push_back(pos[0]);
}
}
return ans;
}
