#include <bits/stdc++.h>
#define REP(a,b,c) for(int a=b; a<(int)c; a++)
#define rep(a,b) REP(a,0,b)
#define REPR(a,b,c) for(int a=b; a>(int)c; a++)
#define repr(a,b) REPR(a,b,0)
#define pb(a) push_back(a)
#define show(a) rep(iiixxxaaaa, a.size()) cout << a[i] << ", ";
typedef long long int llint;
using namespace std;

int f(int n){
  if(n==1) return 0;
  int rtn = f(n/2)^f((n+1)/2)^1;
  return n<3 ? rtn : (rtn | (f(n/3)^f((n+1)/3)^f((n+2)/3)^1));
}

int main(){
  int N;
  cin >> N;
  cout << (f(N)==1 ? "A" : "B") << endl;
  return 0;
}