import std.algorithm, std.conv, std.range, std.stdio, std.string;

void main()
{
  auto n = readln.chomp.to!size_t;
  auto c = readln.split.to!(int[]).filter!"a > 0".array;
  n = c.length;

  if (n == 0) {
    writeln("B");
    return;
  }

  auto b = c.count!"a >= 2";
  writeln(b == 0 && n % 2 == 0 || b == 1 && n % 2 == 1 || b >= 2 ? "B" : "A");
}