#include <bits/stdc++.h>
#include "combo.h"
using namespace std;
using ll = long long;
#define pb push_back
#define mkp make_pair
#define ff first
#define ss second
#define all(a) a.begin(), a.end()
#define sz(a) (int)(a.size())
#define clr(a, b) memset(a, b, sizeof(a))
#define REP(i, a, b) for(int i=(int)(a); i<(int)(b); ++i)
#define REPD(i, a, b) for(int i=(int)(a)-1; i>=(int)(b); --i)
#define FOR(it,c) for ( __typeof((c).begin()) it=(c).begin(); it!=(c).end(); it++ )
template<typename T> inline bool chkmin(T &a, const T &b) { return a > b ? a = b, 1 : 0; }
template<typename T> inline bool chkmax(T &a, const T &b) { return a < b ? a = b, 1 : 0; }
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
string guess_sequence(int N) {
string res = "";
int ret = press("AB");
if(ret >= 1) {
ret = press("A");
res += (ret == 1) ? 'A' : 'B';
} else {
ret = press("X");
res += (ret == 1) ? 'X' : 'Y';
}
char c[] = {'A', 'B', 'X', 'Y'};
char f[3];
REP(i, 1, N) {
string q = res;
REP(j, 0, 4) {
if(res[0] != c[j]) {
if(sz(q) > sz(res)) {
f[1] = c[j];
REP(k, 0, 4) {
if(c[k] != res[0]) q += res + c[j] + c[k];
}
}
else q += c[j], f[0] = c[j];
}
}
REP(j, 0, 4) {
if(c[j] == res[0]) continue;
int done = 0;
REP(k, 0, 2) {
if(c[j] == f[k]) done = 1;
}
if(!done) f[2] = c[j];
}
if(sz(q) > 4*N) {
ret = press(res + "A" + res + "B");
if(ret >= i+1) {
ret = press(res + "A");
if(ret == i+1)
res += 'A';
else
res += 'B';
} else {
ret = press(res + "X");
if(ret == i+1)
res += 'X';
else
res += 'Y';
}
} else {
ret = press(q);
if(ret == i+1) {
res += f[0];
} else if(ret == i+2) {
res += f[1];
} else {
res += f[2];
}
}
}
return res;
}
