#include "bits/stdc++.h"
#define FAST ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define ff first
#define ss second
#define ll long long
using namespace std;
int press(string p);
// {
// cout << "? " << p << endl;
// int ans; cin >> ans;
// return ans;
// }
string guess_sequence(int N)
{
int p = press("AB");
string s = " ";
if(p) s[0] = ( press("A") ? 'A' : 'B');
else s[0] = ( press("X") ? 'X' : 'Y');
string t = "ABXY";
if(s[0] == 'B') swap(t[0], t[1]);
if(s[0] == 'X') swap(t[0], t[2]);
if(s[0] == 'Y') swap(t[0], t[3]);
string q = "";
for(int i = 1; i < N - 1; i++)
{
q = s + t[1] + t[1] + string(t[0], N - 2 - i) + s + t[1] + t[2] + string(t[0], N - 2 - i) + s + t[1] + t[3] + string(t[0], N - 2 - i) + s + t[2] + string(t[0], N - 2 - i);
p = press(q);
if(p == i + 2) s = s + t[1];
else if(p == i + 1) s = s + t[2];
else s = s + t[3];
}
q = s + t[1];
if(press(q) == N) s = s + t[1];
else s = s + (press(s + t[2]) == N ? t[2] : t[3]);
return s;
}
// int main()
// {
// FAST;
// int n; cin >> n;
// string s = guess_sequence(n);
// cout << s << "\n";
// return 0;
// }
