#include <bits/stdc++.h>
using namespace std;

int main() {
  long long N; cin >> N;
  string Ans;
  auto f = [&](auto f, long long X, string S) -> void {
    if (X == N) {
      Ans = S;
      return;
    }
    if (X > N) return;
    f(f, X * 2 + 1, S + 'A');
    f(f, X * 3 + 1, S + 'B');
  };
  f(f, 1, "");
  cout << Ans << endl;
}