#!/usr/bin/env python3

import array


def mex(s):
    m = 0
    while m in s:
        m += 1
    return m


def can_a_win(n):
    gs = array.array("I", (0 for _ in range(n + 1)))
    for i in range(2, n + 1):
        s = set()
        s.add(gs[i // 2] ^ gs[(i + 1) // 2])
        if i >= 3:
            s.add(gs[i // 3] ^ gs[(i + 1 // 3)] ^ gs[(i + 2 // 3)])
        gs[i] = mex(s)
    return gs[n] > 0


def main():
    print("A" if can_a_win(int(input())) else "B")


if __name__ == '__main__':
    main()