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

int main(){
    int n;
    cin>>n;
    vector<int> dp(n+1,0);
    dp[2]=1;
    for(int i=3;i<=n;i++){
        set<int> S;
        S.insert(dp[i/2]^dp[(i+1)/2]);
        S.insert(dp[i/3]^dp[(i+1)/3]^dp[(i+2)/3]);
        while(S.count(dp[i]))dp[i]++;
    }
    cout<<(dp[n]?'A':'B')<<endl;
}