#include <bits/stdc++.h>
#include "combo.h"
using namespace std;
// A, B, X, Y
string strend(string s, int n) {
while ((int)s.size() < n) s+=s[0];
return s;
}
string guess_sequence(int n) {
string ans;
vector<string> v={"A", "B", "X", "Y"};
if (press("AB") > 0) {
if (press("A") > 0) ans+="A";
else ans+="B";
} else {
if (press("X") > 0) ans+="X";
else ans+="Y";
}
for (int j=0; j<4; ++j) {
if (v[j] == string(1, ans[0])) {
v.erase(v.begin()+j);
break;
}
}
for (int i=1; i+1<n; ++i) {
string tmp=strend(ans+v[0]+v[0], n)+strend(ans+v[0]+v[1], n)+strend(ans+v[1]+v[0], n);
int k=press(tmp)-i;
if (k == 0) {
ans+=v[2];
continue;
} else if (k == 1) {
tmp=strend(ans+v[0]+v[0], n);
int x=press(tmp)-i;
if (x == 0) ans+=v[1]+v[0];
else if (x == 1) ans+=v[0]+v[1];
else ans+=v[0]+v[0];
++i;
} else if (k == 2) {
tmp=strend(ans+v[0]+v[0], n);
int x=press(tmp)-i;
if (x == 0) ans+=v[1]+v[0];
else if (x == 1) ans+=v[0]+v[1];
else ans+=v[0]+v[0];
++i;
}
}
assert(n-ans.size() <= 1);
if ((int)ans.size() < n) {
if (press(ans+v[0]) == n) ans+=v[0];
else if (press(ans+v[1]) == n) ans+=v[1];
else ans+=v[2];
}
return ans;
}
