#include <bits/stdc++.h>

using namespace std;

using ll = long long;

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n;
    ll x;
    cin >> n >> x;
    vector<ll> a(n), sum(n + 1, 0);

    for (int i = 0; i < n; ++i) {
        cin >> a[i];
        sum[i + 1] = sum[i] + a[i];
    }

    vector<int> nex_row(n + 1, 0), nex_col(n + 1, 0);
    for (int i = 0; i <= n; ++i) {
        nex_row[i] = i + 1;
        nex_col[i] = i - 1;
    }

    for (int d = 1; d < n; ++d) {
        vector<int> tmp_row = nex_row, tmp_col = nex_col;
        for (int i = 0; i <= n - d; ++i) {
            if (nex_row[i] > i + d || nex_col[i + d] < i) continue;

            {
                int idx = lower_bound(sum.begin(), sum.begin() + i, sum[i] - x) - sum.begin();
                tmp_col[i + d] = min(tmp_col[i + d], idx - 1);
            }

            {
                int idx = upper_bound(sum.begin() + i + d, sum.end(), x + sum[i + d]) - sum.begin();
                tmp_row[i] = max(tmp_row[i], idx);         
            }
        }
        nex_row = move(tmp_row);
        nex_col = move(tmp_col);
    }
    cout << ((nex_row[0] > n || nex_col[n] < 0) ? "A" : "B") << "\n";
    return 0;
}