#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
const int inf = 1012345678;
int main() {
	int N; long long X;
	cin >> N >> X;
	vector<long long> A(N);
	for (int i = 0; i < N; ++i) cin >> A[i];
	vector<long long> S(N + 1);
	for (int i = 0; i < N; ++i) S[i + 1] = S[i] + A[i];
	vector<vector<bool> > dp(N + 1, vector<bool>(N + 1, true));
	vector<vector<int> > sl(N + 1, vector<int>(N + 1));
	vector<vector<int> > sr(N + 1, vector<int>(N + 1));
	for (int i = 1; i <= N; ++i) {
		for (int l = 0; l <= N - i; ++l) {
			int r = l + i;
			dp[l][r] = false;
			int pr = lower_bound(S.begin(), S.end(), S[l] + X + 1) - S.begin();
			if (pr >= r) pr = r;
			if (sl[l + 1][r] != sl[pr][r]) dp[l][r] = true;
			/*
			for (int j = l + 1; j < pr; ++j) {
				if (!dp[j][r]) dp[l][r] = true;
			}
			*/
			int pl = lower_bound(S.begin(), S.end(), S[r] - X) - S.begin();
			if (pl <= l) pl = l + 1;
			if (sr[l][pl - 1] != sr[l][r - 1]) dp[l][r] = true;
			/*
			for (int j = pl; j < r; ++j) {
				if (!dp[l][j]) dp[l][r] = true;
			}
			*/
			sl[l][r] = sl[l + 1][r] + (!dp[l][r] ? 1 : 0);
			sr[l][r] = sr[l][r - 1] + (!dp[l][r] ? 1 : 0);
		}
	}
	cout << (dp[0][N] ? "A" : "B") << endl;
	return 0;
}