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