#include "combo.h"
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define str string
str guess_sequence(int n) {
str res = "";
vector<char> c(4);
c = {'A', 'B', 'X', 'Y'};
str p = "";
p.push_back(c[0]);
p.push_back(c[1]);
ll r = press(p);
if (r==0) {
char a1, a2;
a1 = c[2];
a2 = c[3];
c[2] = c[0];
c[3] = c[1];
c[0]=a1;
c[1]=a2;
}
p = "";
p.push_back(c[0]);
r = press(p);
if (r==0) {
char aux = c[1];
c[1] = c[0];
c[0]=aux;
}
res.push_back(c[0]);
if (n==1) return res;
ll t = 1;
for (int i=1; i<(n-1); i++) {
p = "";
p += res;
p.push_back(c[3]);
p.push_back(c[1]);
//AA
p += res;
p.push_back(c[3]);
p.push_back(c[2]);
//AB
p += res;
p.push_back(c[3]);
p.push_back(c[3]);
//AY
p += res;
p.push_back(c[2]);
r = press(p);
r-=t;
r++;
res.push_back(c[r]);
t++;
}
p = res;
p.push_back(c[1]);
r = press(p);
if (r==n) {
res.push_back(c[1]);
} else {
p = res;
p.push_back(c[2]);
r = press(p);
if (r==n) {
res.push_back(c[2]);
} else {
res.push_back(c[3]);
}
}
return res;
}
