#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
#define o_set tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update>
//#define int ll
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int press(string p);
string guess_sequence(int N){
vector<char> k={'A','B','X','Y'};
string sol="";
int a=press("AB");
if(a){
int b=press("A");
if(b){
sol="A";
k.erase(k.begin());
}else{
sol="B";
k.erase(k.begin()+1);
}
}else{
int b=press("X");
if(b){
sol="X";
k.erase(k.begin()+2);
}else{
sol="Y";
k.erase(k.begin()+3);
}
}
if(N==1)return sol;
for(int i=1;i<N-1;i++){
int z=press(sol+k[0]+k[0]+sol+k[0]+k[1]+sol+k[0]+k[2]+sol+k[1]);
if(z==i)sol+=k[2];
else if(z==(i+1))sol+=k[1];
else sol+=k[0];
}
a=press(sol+k[0]+sol+k[1]);
if(a==N-1)return sol+k[2];
a=press(sol+k[0]);
if(a==N)return sol+k[0];
return sol+k[1];
}
/*
signed main(){
ios_base::sync_with_stdio(0);cin.tie(0);
cout<<guess_sequence(5);
}*/
