#include <bits/stdc++.h>

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

struct SegTree {
	std::vector<int> data;
	int n;
	SegTree (int n_) {
		for (n = 1; n < n_; n <<= 1);
		data.resize(n << 1);
	}
	void set(int i, int val) {
		for (data[i += n] = val; i >>= 1; ) data[i] = data[i << 1] + data[i << 1 | 1];
	}
	int sum(int l, int r) {
		int res = 0;
		for (l += n, r += n; l < r; l >>= 1, r >>= 1) {
			if (r & 1) res += data[--r];
			if (l & 1) res += data[l++];
		}
		return res;
	}
};

int main() {
	int n = ri(), 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] = a[i] + sum[i];
	
	int left[n + 1], right[n + 1];
	for (int i = 0; i <= n; i++) {
		left[i] = std::lower_bound(sum, sum + n + 1, sum[i] - x) - sum;
		right[i] = std::upper_bound(sum, sum + n + 1, sum[i] + x) - sum - 1;
	}
	
	std::vector<SegTree> r0(n + 1, SegTree(n + 1));
	std::vector<SegTree> r1(n + 1, SegTree(n + 1));
	
	std::vector<SegTree> r2(n + 1, SegTree(n + 1));
	std::vector<SegTree> r3(n + 1, SegTree(n + 1));
	
	bool dp[n + 1][n + 1][2];
	memset(dp, 0, sizeof(dp));
	for (int i = 0; i <= n; i++) {
		dp[i][i][0] = true;
		r0[i].set(i, true);
		r1[i].set(i, true);
		dp[i][i][1] = false;
	}
	for (int i = 1; i <= n; i++) {
		for (int j = 0; j + i <= n; j++) {
			int k = j + i;
			dp[j][k][1] = true;
			// dp[j][k][?]
			// eat left -> dp[j + 1, right[j]][k]
			if (j < right[j] && r1[k].sum(j + 1, right[j] + 1) != right[j] - j) {
				dp[j][k][1] = false;
			}
			if (j < right[j] && r3[k].sum(j + 1, right[j] + 1)) {
				dp[j][k][0] = true;
			}
			// eat right -> dp[j][[left[k], k)]
			if (left[k] < k && r0[j].sum(left[k], k) != k - left[k]) {
				dp[j][k][1] = false;
			}
			if (left[k] < k && r2[j].sum(left[k], k)) {
				dp[j][k][0] = true;
			}
			r0[j].set(k, dp[j][k][0]);
			r1[k].set(j, dp[j][k][0]);
			r2[j].set(k, dp[j][k][1]);
			r3[k].set(j, dp[j][k][1]);
		}
	}
	/*
	for (int i = 0; i < n; i++) {
		for (int j = i + 1; j <= n; j++) {
			std::cerr << i << "," << j << " : " << dp[i][j][0] << "," << dp[i][j][1] << std::endl;
		}
	}*/
	std::cout << (dp[0][n][0] ? "A" : "B") << std::endl;
	return 0;
}