// #define local
#include <bits/stdc++.h>
using namespace std;
#ifdef local
int press(string p) {
cout << p;
int ret;
cin >> ret;
return ret;
}
string guess_sequence(int);
signed main() {
int n;
cin >> n;
cout << guess_sequence(n) << '\n';
return 0;
}
#else
#include <combo.h>
#endif
string guess_sequence(int n) {
string ans, tmp;
int ret, len = 1;
ret = press("AB");
if (ret == 1) {
ret = press("A");
if (ret == 1) ans = "A";
else ans = "B";
}
else {
ret = press("X");
if (ret == 1) ans = "X";
else ans = "Y";
}
vector<string> L;
if ("A" != ans) L.push_back("A");
if ("B" != ans) L.push_back("B");
if ("X" != ans) L.push_back("X");
if ("Y" != ans) L.push_back("Y");
string P[4];
P[0] = L[0] + L[0], P[1] = L[0] + L[1], P[2] = L[0] + L[2];
P[3] = L[1];
for (int i = 2; i < n; i++) {
tmp = "";
for (int j = 0; j < 4; j++)
tmp += (ans + P[j]);
ret = press(tmp);
if (ret == len + 2) ans += L[0];
else if (ret == len + 1) ans += L[1];
else if (ret == len) ans += L[2];
len++;
}
ret = press(ans + L[0] + ans + L[1]);
if (ret == len+1) {
ret = press(ans + L[0]);
if (ret == len+1) ans += L[0];
else ans += L[1];
}
else if (ret == len)
ans += L[2];
return ans;
}
