#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
#define all(x) x.begin(),x.end()
#define mp make_pair
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<int,int> pii;
int press(string a);
string guess_sequence(int N){
string s;
s.resize(1);
if(press ("XY") > 0){
if(press("X") > 0)s[0] = 'X';
else s[0] = 'Y';
}else{
if(press("A") > 0)s[0] = 'A';
else s[0] = 'B';
}
vector<char> k = {'A','B','X','Y'};
for(int i = 1; i < 4; i++)if(k[i] == s[0]) swap(k[0],k[i]);
for(int i = 1; i < N-1; i++){
string q = s;
q+=k[1];
q+=s+k[2]+k[1];
q+=s+k[2]+k[2];
q+=s+k[2]+k[3];
int kek = press(q);
if(kek == i){
s.pb(k[3]);
}else if(kek == i+1){
s.pb(k[1]);
}else{
s.pb(k[2]);
}
}
if(press(s+k[1]) == N){
s.pb(k[1]);
}else if(press(s+k[2]) == N){
s.pb(k[2]);
}else{
s.pb(k[3]);
}
return s;
}
