#include<bits/stdc++.h>
#include <combo.h>
using namespace std;
#define rc(x) return cout<<x<<endl,0
#define pb push_back
#define dbg(x) cout << #x << '=' << x << '\n';
#define ll long long
#define sz size()
#define x first
#define y second
#define pi pair <int, int>
#define pii pair <int, pi>
#define vi vector <int>
const ll mod = 1e9 + 7;
string guess_sequence(int n){
string s="";
vector <string> ch={"A", "B", "X", "Y"};
if(press("A")) s="A";
else if(press("B")) s="B";
else if(press("X")) s="X";
else s="Y";
// cout<<s<<endl;
vector <string> use;
for(int i=0; i<=3; i++) if(ch[i]!=s) use.pb(ch[i]);
//for(string i: use) cout<<"x"<<i<<endl;
for(int i=1; i<n-1; i++){
string xd=s+use[0]+s+use[1]+use[0]+s+use[1]+use[1]+s+use[1]+use[2];
// cout<<s<<" "<<xd;//<<endl;
int q=press(xd); //cout<<" "<<q<<endl;
if(q-2==i) s=s+use[1];
else if(q-1==i) s=s+use[0];
else s=s+use[2];
//cout<<s<<endl;
}//cout<<s<<endl;
int q=press(s+use[0]+s+use[1]);
if(q==n-1){
return (s+use[2]);
}
else{
q=press(s+use[0]);
if(q==n-1) return (s+use[1]);
else return (s+use[0]);
}
}
