오답인 이유가 궁금합니다

import java.util.*;

public class Main {
	public static void main(String[] args) {
		Main t = new Main();
		
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		
		int[] arrA = new int[N];
		for (int i = 0; i < N; i++) {
			arrA[i] = sc.nextInt();
		}
		int[] arrB = new int[N];
		for (int i = 0; i < N; i++) {
			arrB[i] = sc.nextInt();
		}
		
		System.out.println(t.solution(N, arrA, arrB));
	}
	
	public String solution(int N, int[] arrA, int[] arrB) {
		String answer = "";
		
		for (int i = 0; i < N; i++) {
			switch (arrA[i] - arrB[i]) {
				case -1: case 2: {
					answer += "B";
					break;
				}
				case 1: case -2: {
					answer += "A";
					break;
				}
				case 0: {
					answer += "D";
					break;
				}
			}
		}
		return answer;
	}
}