import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int x = sc.nextInt();
        int[] cals = new int[n];
        for (int i = 0; i < n; i++) {
            cals[i] = sc.nextInt();
        }
        boolean[][] dp = new boolean[n][n];
        for (int i = 1; i < n; i++) {
            for (int j = 0; j + i < n; j++) {
                int sum = 0;
                for (int k = j; !dp[j][j + i]; k++) {
                    sum += cals[k];
                    if (sum > x) {
                        break;
                    }
                    dp[j][j + i] = !dp[k + 1][j + i];
                }
                sum = 0;
                for (int k = j + i; !dp[j][j + i]; k--) {
                    sum += cals[k];
                    if (sum > x) {
                        break;
                    }
                    dp[j][j + i] = !dp[j][k - 1];
                }
            }
        }
        if (dp[0][n - 1]) {
            System.out.println("A");
        } else {
            System.out.println("B");
        }
    }
}