#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include "combo.h"
using namespace std;
using namespace __gnu_pbds;
#define watch(x) cout<<(#x)<<"="<<(x)<<'\n'
#define mset(d,val) memset(d,val,sizeof(d))
#define setp(x) cout<<fixed<<setprecision(x)
#define forn(i,a,b) for(int i=a;i<b;i++)
#define fore(i,a,b) for(int i=a;i<=b;i++)
#define pb push_back
#define F first
#define S second
#define INF 2e14
#define MOD 998244353
#define pqueue priority_queue
#define fbo find_by_order
#define ook order_of_key
typedef long long ll;
typedef pair<ll,ll> ii;
typedef vector<ll> vi;
typedef vector<ii> vii;
typedef tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update> pbds;
#define MAXN 100005
char ch[4]={'A','B','X','Y'};
string guess_sequence(int n){
char x;
string tmp;
for(int i=0;i<4;i++)
{
x=ch[i];
if(press(""+x)==1)
{
tmp+=x;
break;
}
}
for(int i=1;i<n;i++)
{
for(int j=0;j<4;j++)
{
if(ch[j]!=x)
{
if(press(tmp+ch[j])==i+1)
{
tmp+=ch[j];
break;
}
}
}
}
return tmp;
}
