#include <bits/stdc++.h>
#include "combo.h"
using namespace std;
#define ull unsigned long long
#define ll long long
#define ld long double
#define pb push_back
#define f first
#define s second
#define sz(x) (int)x.size()
#define all(x) x.begin(),x.end()
#define pii pair<int,int> //
#define pll pair<ll,ll>
#define pld pair<ld,ld>
#define pdd pair<double,double>
#define mp make_pair
#define AmirMakaM ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
// solve it
//const ull SEED = chrono::steady_clock::now().time_since_epoch().count();
//mt19937_64 mrand(SEED);
//ull rnd(ull x = ~(0ull)) {return mrand() % x;}
const ll MOD = 1e9 + 7;
const ll INF = 1e16+20;
const int inf = 1e9 + 7;
//const ll N = 1e5+1;
const ll M = 2e3+1;
const double pi = 2*acos(0.0);
const int dx[] = {1,-1,0,0}, dy[] = {0,0,1,-1};
string guess_sequence(int n) {
string a[4] = {"A","B","X","Y"};
if(n == 1) {
for(int j=0; j<4; j++) {
if(j == 3 || press(a[j]) == 1) {
return a[j];
}
}
}
string ans = "";
int id = -1;
string cur1 = a[1]+a[0];
int cnt1 = press(cur1);
if(cnt1) {
string cur2 = a[1];
int cnt2 = press(cur2);
if(cnt2) {
ans += a[1], id = 1;
} else {
ans += a[0], id = 0;
}
} else {
string cur2 = a[2];
int cnt2 = press(cur2);
if(cnt2) {
ans += a[2], id = 2;
} else {
ans += a[3], id = 3;
}
}
vector<string> b;
for(int j=0; j<4; j++) {
if(id!=j) b.pb(a[j]);
}
for(int i=2; i<=n-1; i++) {
string cur = ans+b[0]+ans+b[1]+b[0]+ans+b[1]+b[1]+ans+b[1]+b[2];
int cnt = press(cur);
if(cnt == i-1) {
ans += b[2];
} else if(cnt == i) {
ans += b[0];
} else {
ans += b[1];
}
}
for(int i=0; i<3; i++) {
if(i == 2 || press(ans+b[i]) == n) {
ans += b[i];
break;
}
}
return ans;
}
