#include "combo.h"
#include "bits/stdc++.h"
using namespace std;
#define FAST ios_base::sync_with_stdio(false); cin.tie(0);
#define pb push_back
#define eb emplace_back
#define ins insert
#define f first
#define s second
#define cbr cerr<<"hi\n"
#define mmst(x, v) memset((x), v, sizeof ((x)))
#define siz(x) ll(x.size())
#define all(x) (x).begin(), (x).end()
#define lbd(x,y) (lower_bound(all(x),y)-x.begin())
#define ubd(x,y) (upper_bound(all(x),y)-x.begin())
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count()); //can be used by calling rng() or shuffle(A, A+n, rng)
inline long long rand(long long x, long long y) { return rng() % (y+1-x) + x; } //inclusivesss
string inline to_string(char c) {string s(1,c);return s;} template<typename T> inline T gcd(T a,T b){ return a==0?llabs(b):gcd(b%a,a); }
using ll=long long;
using ld=long double;
#define FOR(i,s,e) for(ll i=s;i<=ll(e);++i)
#define DEC(i,s,e) for(ll i=s;i>=ll(e);--i)
using pi=pair<ll,ll>; using spi=pair<ll,pi>; using dpi=pair<pi,pi>;
#define LLINF ((long long)1e18)
#define INF int(1e9+1e6)
#define MAXN (300006)
std::string guess_sequence(int n) {
string ans = "";
ll val = press("AB");
if(val>=1){
val=press("A");
if(val==1) ans = 'A';
else ans = 'B';
}else{
val = press("X");
if(val==1) ans = 'X';
else ans = 'Y';
}
vector<string> pos;
for(auto i:{"A","B","X","Y"}) if(ans != i) pos.eb(i);
FOR(i,2,n-1){
ll val=press(ans+pos[0]+pos[0]+ans+pos[0]+pos[1]+ans+pos[0]+pos[2]+ans+pos[1]+to_string(ans[0]));
if(val == ans.size() + 2) ans += pos[0];
else if(val == ans.size() + 1) ans += pos[1];
else ans += pos[2];
}
if(n>1){
ll val=press(ans+pos[0]+ans+pos[1]);
if(val==ans.size()+1){
ll val=press(ans+pos[0]);
if(val==ans.size()+1)ans+=pos[0];
else ans+=pos[1];
}else{
ans+=pos[2];
}
}
return ans;
}
