package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var sc = bufio.NewScanner(os.Stdin)

func Scanner() string {
	sc.Scan()
	return sc.Text()
}
func main() {
	buf := make([]byte, 0)
	sc.Buffer(buf, 100000007)
	sc.Split(bufio.ScanWords)
	n, _ := strconv.Atoi(Scanner())
	x, _ := strconv.Atoi(Scanner())
	a := make([]int, 5000)
	for i := 0; i < n; i++ {
		a[i], _ = strconv.Atoi(Scanner())
	}

	l := make([]int, 5000)
	r := make([]int, 5000)
	sum := 0
	b := 0
	c := 0

	for b != n {
		for c != n && sum+a[c] <= x {
			sum += a[c]
			c++
		}
		l[b] = c - b
		sum -= a[b]
		b++
	}
	b = n - 1
	c = n - 1
	sum = 0
	for c >= 0 {
		for b != 0 && sum+a[b] <= x {
			sum += a[b]
			b--
		}
		r[c] = c - b
		sum -= a[c]
		c--
	}

	dp_l := make([][]int, 5000)
	for i := 0; i < n; i++ {
		dp_l[i] = make([]int, 5001)
	}
	dp_r := make([][]int, 5000)
	for i := 0; i < n; i++ {
		dp_r[i] = make([]int, 5001)
	}
	left := 0
	right := 0
	q := 0
	for i := 0; i <= n; i++ {
		for j := 0; j < n; j++ {
			if i == 0 {
				dp_l[j][i] = 0
				dp_r[j][i] = 0
				continue
			}
			left = j
			right = j + i - 1
			if right >= n {
				break
			}
			q = min(l[left], i-1)
			p := dp_r[right][i-1] - dp_r[right][i-q-1]
			if p != q {
				dp_l[left][i] = dp_l[left][i-1] + 1
				dp_r[right][i] = dp_r[right][i-1] + 1
				continue
			}

			q = min(r[right], i-1)
			p = dp_l[left][i-1] - dp_l[left][i-q-1]
			if p != q {
				dp_l[left][i] = dp_l[left][i-1] + 1
				dp_r[right][i] = dp_r[right][i-1] + 1
				continue
			}
			dp_l[left][i] = dp_l[left][i-1]
			dp_r[right][i] = dp_r[right][i-1]
		}
	}
	ans := "A"
	if dp_l[0][n] == dp_r[0][n-1] {
		ans = "B"
	}
	fmt.Println(ans)
}

func min(x int, y int) int {
	if x >= y {
		return y
	} else {
		return x
	}
}