#include<iostream>
#include<set>
using namespace std;
int memo[101];
int f(int n)
{
	if(memo[n]>=0)return memo[n];
	set<int>S;
	S.insert(f(n/2)^f(n-n/2));
	if(n>=3)
	{
		if(n%3==1)S.insert(f(n/3+1));
		else S.insert(f(n/3));
	}
	if(S.find(0)==S.end())return memo[n]=0;
	else if(S.find(1)==S.end())return memo[n]=1;
	else return memo[n]=2;
}
main()
{
	for(int i=2;i<=100;i++)memo[i]=-1;
	int N;cin>>N;
	cout<<(f(N)?"A":"B")<<endl;
}