#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';
}
bool weird = 0;
vector<string> pos;
for(auto i:{"A","B","X","Y"}) if(ans != i) pos.eb(i);
string one="", two="";
ll pre = 0;
auto gen=[&](string x,string y){
while(x.size() < n) x += y;
return x;
};
auto times=[&](string x,ll y){
string ret="";
FOR(i,1,y)ret+=x;
return ret;
};
FOR(i,2,n){
if(weird){
vector<string> other;
for(auto i:pos) if(one != i) other.eb(i);
ll val = press(gen(ans + times(one, pre - siz(ans)), other[0]) +
gen(ans + times(one, pre - siz(ans)), other[1]));
if(val == ans.size()){
while(ans.size() != pre) ans += two;
}else{
while(ans.size() != pre) ans += one;
}
pre = val, one = other[0], two = other[1];
i = pre;
}else{
ll val = press(gen(ans,pos[0])+gen(ans,pos[1]));
if(val == ans.size()){
ans += pos[2];
}else{assert(val>ans.size());
// weird time
weird = 1;
pre = val, one = pos[0], two = pos[1];
i = pre;
}
}
}
if(ans.size() < n){ assert(weird);
ll val=press(ans + one);
if(val > ans.size()){
while(ans.size() < n) ans += one;
}else {
while(ans.size() < n) ans += two;
}
}assert(ans.size()==n);
return ans;
}
