#include "combo.h"
#include<bits/stdc++.h>
using namespace std;
std::string guess_sequence(int N)
{
char primu;
if(press("AB")==0)
{
if(press("X"))
primu = 'X';
else
primu = 'Y';
}
else
{
if(press("A"))
primu = 'A';
else
primu = 'B';
}
vector<char> ch = {'A','B','X','Y'};
for(int i=0;i<4;i++)
{
if(ch[i]==primu)
{
ch.erase(ch.begin()+i);
break;
}
}
string s;
s.push_back(primu);
if(N==1)
return s;
for(int i=1;i<N-1;i++)
{
string p = "";
p += s;p.push_back(ch[0]);
for(int j=0;j<3;j++)
{
p += s;
p.push_back(ch[1]);
p.push_back(ch[j]);
}
int x = press(p);
if(x == (int)s.size())
{
s.push_back(ch[2]);
}
else if(x == (int)s.size() + 1)
{
s.push_back(ch[0]);
}
else
{
s.push_back(ch[1]);
}
}
assert((int)s.size() == N-1);
if(press(s+ch[0])==N)
return s + ch[0];
else if(press(s+ch[1])==N)
return s + ch[1];
else
return s + ch[2];
}
