import std.algorithm, std.array, std.container, std.range, std.bitmanip;
import std.numeric, std.math, std.bigint, std.random, core.bitop;
import std.string, std.regex, std.conv, std.stdio, std.typecons;

void main()
{
  auto n = readln.chomp.to!int;

  auto memo = new int[](n + 1);
  memo[1] = 0;
  if (n >= 2) memo[2] = 1;
  if (n >= 3) memo[3] = 2;

  foreach (i; 4..n+1) {
    int a2 = calc2(i, memo);
    int a3 = calc3(i, memo);
    memo[i] = mex(a2, a3);
  }

  writeln(memo[n] == 0 ? "B" : "A");
}

int calc2(int n, int[] memo)
{
  if (n % 2 == 0)
    return memo[n / 2] ^ memo[n / 2];
  else
    return memo[n / 2] ^ memo[n / 2 + 1];
}

int calc3(int n, int[] memo)
{
  if (n % 3 == 0)
    return memo[n / 3] ^ memo[n / 3] ^ memo[n / 3];
  else if (n % 3 == 1)
    return memo[n / 3] ^ memo[n / 3] ^ memo[n / 3 + 1];
  else
    return memo[n / 3] ^ memo[n / 3 + 1] ^ memo[n / 3 + 1];
}

int mex(int a2, int a3)
{
  auto r = 0;
  while (r == a2 || r == a3) ++r;
  return r;
}