#include <bits/stdc++.h>
#include "combo.h"
using namespace std;
string guess_sequence( int N )
{
string s = "";
string a = "ABXY";
vector<char> bt;
if( press("A") > 0 ) s += "A";
else if( press("B") > 0 ) s += "B";
else if( press("X") > 0 ) s += "X";
else s += "Y";
if( N == 1 ) return s;
for( auto c : a ) if( s[0] != c ) bt.push_back( c );
for( int i=1;i<N-1;i++ )
{
string tp = s+bt[0] + s+bt[1]+bt[0] + s+bt[1]+bt[1] + s+bt[1]+bt[2];
int sz = s.size();
int res = press(tp);
if( res == sz+1 ) s += bt[0];
else if( res == sz+2 ) s += bt[1];
else s += bt[2];
}
if( press(s+bt[0]) == N ) s += bt[0];
else if( press(s+bt[1]) == N ) s += bt[1];
else s += bt[2];
return s;
}
