#include <bits/stdc++.h>

using namespace std;

using i64 = long long;

template <typename T>
struct BIT{
    vector<T> elm;
    BIT(int n, T init = T()) : elm(n + 1, init){
    }

    // [0, x)
    T sum(int x){
        T val = 0;
        for(; x > 0; x -= x & -x)
            val += elm[x];
        return val;
    }

    // [l, r)
    T sum(int l, int r){
        return sum(r) - sum(l);
    }

    void add(int x, T val){
        for(++x; x < elm.size(); x += x & -x)
            elm[x] += val;
    }
};

signed main(){
    int n, x;
    cin >> n >> x;
    vector<int> v(n);
    for(auto& w : v)
        cin >> w;

    vector<i64> r(n + 1, 0);
    for(int i = 0; i < n; ++i)
        r[i + 1] = r[i] + v[i];

    vector<int> nex(n, n), prev(n + 1, n);
    for(int i = 0; i < n; ++i){
        auto it = upper_bound(r.begin(), r.end(), r[i + 1] + x);
        int idx = distance(r.begin(), it);
        nex[i] = idx - 1;
        prev[idx - 1] = min(prev[idx - 1], i);
    }

    for(int i = n; i > 0; --i)
        prev[i - 1] = min(prev[i - 1], prev[i]);

    vector<BIT<int>> a(n, BIT<int>(n)), b(n, BIT<int>(n));


    for(int k = 1; k < n; ++k)
        for(int i = 0, j = k; j < n; ++i, ++j){
            bool f = false;

            // dp[i][j] : dp[i][j - x, j)

            int pj = max(i, prev[j]);
            int ni = min(nex[i], j + 1);


            f |= (a[i].sum(pj, j) != (j - pj));
            f |= (b[j].sum(i + 1, ni) != (ni - (i + 1)));

            if(f){
                a[i].add(j, 1);
                b[j].add(i, 1);
            }
        }

    /*
    for(int i = 0; i < n; ++i){
        for(int j = 0; j < n; ++j)
            cout << a[i].sum(j, j + 1) << " \n"[j == n - 1];
    }
    cout << endl;
     */
    cout << (a[0].sum(n - 1, n) ? "A" : "B") << endl;
}