#include<iostream>
#include<combo.h>
using namespace std;
string guess_sequence(int N)
{
int x,i;
string s;
char ch[4]={'A','B','X','Y'};
if(press("AB")==1)
{
if(press("A")==1)
x=1;
else
x=2;
}
else
{
if(press("C")==1)
x=3;
else
x=4;
}
s+=ch[x];
if(N==1)
return s;
swap(ch[x],ch[3]);
for(i=1;i<N-1;i++)
{
x=press(s+ch[0]+ch[0]+s+ch[0]+ch[1]+s+ch[0]+ch[2]+s+ch[1]);
if(x==i+2)
s+=ch[0];
else if(x==i+1)
s+=ch[1];
else
s+=ch[2];
}
if(press(s+ch[0]+s+ch[1])==N)
{
if(press(s+ch[0])==N)
s+=ch[0];
else
s+=ch[1];
}
else
s+=ch[2];
return s;
}
