#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <queue>
#include <algorithm>
#include <numeric>
#include <deque>

using namespace std;

deque<long long> ans;

long long f(long long n){
    if (n == 1) return 0;
    if (n == 0) return 0;
    if (ans[n] != -1) return ans[n];
    set<long long> st;
    long long g=0;
    st.insert(f(n/2) ^ f((n+1)/2));
    if (n >= 3) st.insert(f(n/3) ^ f((n+1)/3) ^ f((n+2)/3));
    while(st.count(g)) g++;
    return ans[n] = g;
}

int main(){

    long long N;
    cin >> N;
    ans.resize(N+1, -1);

    cout << (f(N) != 0 ? "A" : "B") << endl;

    return 0;
}