import core.bitop;
import std.algorithm;
import std.array;
import std.ascii;
import std.container;
import std.conv;
import std.format;
import std.math;
import std.range;
import std.stdio;
import std.string;
import std.typecons;

void main()
{
  int n = readln.chomp.to!int;
  auto c = readln.chomp.split.map!(to!int).filter!"a != 0";
  if (c.any!"a >= 3") {
    "B".writeln;
    return;
  }
  if (c.count(2) >= 2) {
    "B".writeln;
  }
  writeln = c.filter!(a => a <= 2).sum() % 2 == 1 ? "A" : "B";
}