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

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int n; 
    cin >> n;
    vector<int> dp(n+1, 0);
    for (int i = 2; i <= n; i++) {
        set<int> st;
        st.insert(dp[i/3]^dp[(i+1)/3]^dp[(i+2)/3]);
        st.insert(dp[i/2]^dp[(i+1)/2]);
        while (st.count(dp[i])) dp[i]++;
    }
    cout << (dp[n] == 0 ? "B": "A") << "\n";
}