import std.stdio, std.array, std.string, std.conv, std.algorithm;
import std.typecons, std.range, std.random, std.math, std.container;
import std.numeric, std.bigint, core.bitop, core.stdc.stdio;

void main() {
    auto s = readln.split.map!(to!int);
    auto N = s[0];
    auto X = s[1].to!long;
    auto A = readln.split.map!(to!long).array;

    auto B = new long[](N+1);
    foreach (i; 0..N) B[i+1] = B[i] + A[i];

    long sum(int l, int r) {
        if (r < l) return 0;
        return B[r+1] - B[l];
    }

    int calc_left(int l, int r) {
        int hi = r + 1;
        int lo = l;
        while (hi - lo > 1) {
            int mid = (hi + lo) / 2;
            if (sum(l, mid) <= X) lo = mid;
            else hi = mid;
        }
        return lo;
    }

    int calc_right(int l, int r) {
        int hi = r;
        int lo = l - 1;
        while (hi - lo > 1) {
            int mid = (hi + lo) / 2;
            if (sum(mid, r) <= X) hi = mid;
            else lo = mid;
        }
        return hi;
    }

    auto ans = new bool[][](N, N);

    foreach (l; 0..N) {
        int minr = l;
        foreach (r; l+1..N) {
            int nr = calc_right(l, r) - 1;
            if (nr <= minr) {
                ans[l][r] = true;
            } else {
                minr = r;
            }
        }
    }

    foreach (r; 0..N) {
        int maxl = r;
        foreach_reverse (l; 0..r) {
            int nl = calc_left(l, r) + 1;
            if (nl >= maxl) {
                ans[l][r] = true;
            } else {
                maxl = l;
            }
        }
    }

    writeln(ans[0][N-1] ? "A" : "B") ;
}