#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
using pint = pair<int, int>;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define ALL(x) (x).begin(), (x).end()
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template<typename T> bool mmax(T &m, const T q) { if (m < q) {m = q; return true;} else return false; }
template<typename T> bool mmin(T &m, const T q) { if (m > q) {m = q; return true;} else return false; }
template<typename T> istream &operator>>(istream &is, vector<T> &vec){ for (auto &v : vec) is >> v; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; }
#define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;


constexpr int LOSE = 1;
constexpr int WIN = 2;

int main()
{
    int N;
    lint X;
    cin >> N >> X;
    vector<lint> A(N);
    cin >> A;

    vector<lint> B(N + 1);
    REP(i, N) B[i + 1] = B[i] + A[i];

    vector<int> lose_lr(N, N + 1), lose_rl(N + 1, -1);
    vector<vector<int>> win_lose(N + 1, vector<int>(N + 1));

    REP(i, N) win_lose[i][i + 1] = LOSE, lose_lr[i] = i + 1, lose_rl[i + 1] = i;
    REP(i, N + 1) win_lose[i][i] = WIN;

    FOR(d, 2, N + 1) {
        REP(l, N - d + 1) {
            bool f = false;
            int r = l + d;
            int n = upper_bound(ALL(B), B[l] + X) - B.begin() - l - 1;
            int ri = l + n;

            if (ri >= r) f = true;

            if (lose_rl[r] <= ri) f = true;

            auto m = -(lower_bound(ALL(B), B[r] - X) - B.begin() - r);
            int j = r - m;
            if (j <= l) f = true;
            if (lose_lr[l] >= j) f = true;

            if (f) {
                win_lose[l][r] = WIN;
            } else {
                win_lose[l][r] = LOSE;
                mmax(lose_lr[l], r);
                mmin(lose_rl[r], l);
            }
        }
    }
    cout << (win_lose[0][N] == WIN ? "A" : "B") << endl;
}