#include <bits/stdc++.h>

int ri() {
	int n;
	scanf("%d", &n);
	return n;
}

int main() {
	int n = ri();
	int x = ri();
	int a[n];
	for (auto &i : a) i = ri();
	
	int64_t sum[n + 1];
	sum[0] = 0;
	for (int i = 0; i < n; i++) sum[i + 1] = sum[i] + a[i];
	
	bool dp[n + 1][n + 1];
	memset(dp, 0, sizeof(dp));
	for (int i = 0; i <= n; i++) dp[i][i] = false;
	int tail0[n + 1], tail1[n + 1];
	int cur_sum0[n + 1], cur_sum1[n + 1];
	for (int i = 0; i <= n; i++) {
		tail0[i] = tail1[i] = i;
		cur_sum0[i] = cur_sum1[i] = 0;
	}
	for (int i = 1; i <= n; i++) {
		for (int j = 0; j <= n - i; j++) {
			cur_sum0[j + i] += dp[j + 1][j + i];
			while (tail0[j + i] > j && sum[tail0[j + i]] - sum[j] > x)
				cur_sum0[j + i] -= dp[tail0[j + i]--][j + i];
			dp[j][j + i] |= cur_sum0[j + i];
			
			cur_sum1[j] += dp[j][j + i - 1];
			while (tail1[j] < j + i && sum[j + i] - sum[tail1[j]] > x)
				cur_sum1[j] -= dp[j][tail1[j]++];
			dp[j][j + i] |= cur_sum1[j];
			dp[j][j + i] ^= 1;
		}
	}
	puts(dp[0][n] ? "B" : "A");
	return 0;
}