#include "combo.h"
#include<bits/stdc++.h>
using namespace std;
#define pb emplace_back
#define mp make_pair
#define ALL(x) x.begin(), x.end()
#define SZ(x) (int)x.size()
char ltrs[] = {'A', 'B', 'X', 'Y'};
string guess_sequence(int N) {
// cout<<N<<'\n';
string out="";
int a = press("AB");
int b = press("AX");
if(a&&b)out+='A';
if (a&&!b)out+='B';
if (!a&&b)out+='X';
if(!a&&!b)out+='Y';
vector<char> V;
for (int i=0;i<4;++i)if(ltrs[i] != out[0])V.pb(ltrs[i]);
assert(SZ(V) == 3);
for (int i=1;i<N-1;++i){
string q = "";
for (auto i : out)q+=i;
q += V[0];
q += V[0];
for (auto i : out)q+=i;
q += V[0];
q += V[1];
for (auto i : out)q+=i;
q += V[0];
q += V[2];
for (auto i : out)q+=i;
q += V[1];
// cout<<q<<'\n';
int res = press(q);
if (res == SZ(out)){
out += V[2];
}else if (res == SZ(out) + 2){
out += V[0];
}else{
out += V[1];
}
}
out += V[0];
if (press(out) == N)return out;
out.pop_back();
out += V[1];
if (press(out) == N)return out;
out.pop_back();
out += V[2];
return out;
}
