#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

#define RREP(i,s,e) for (i = s; i >= e; i--)
#define rrep(i,n) RREP(i,n,0)
#define REP(i,s,e) for (i = s; i < e; i++)
#define rep(i,n) REP(i,0,n)
#define INF 1e8

typedef long long ll;

int main() {
    int i, n;
    bool dp[101];
    cin >> n;
    dp[1] = false;
    REP (i,2,n+1) {
        if (dp[i/2] == dp[(i+1)/2])
            dp[i] = true;
        else if (i >= 3 && (dp[i/3] != dp[(i+1)/3]) == dp[(i+2)/3])
            dp[i] = true;
        else
            dp[i] = false;
    }
    if (dp[n])
        cout << 'A' << endl;
    else
        cout << 'B' << endl;
    return 0;
}