import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int count = 0;
    for(int i = 0; i < n; i++) {
      int c = sc.nextInt();
      if(c > 2) count++;
    }
    String ans = "A";
    if(count > 0) ans = "B";
    System.out.println(ans);
  }
}