#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
template <typename T> using posteriority_queue = priority_queue<T, vector<T>, greater<T> >;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3fLL;
const double EPS = 1e-8;
const int MOD = 1000000007;
// const int MOD = 998244353;
const int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
// const int dy[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
template <typename T> void unique(vector<T> &a) { a.erase(unique(ALL(a)), a.end()); }
struct IOSetup {
  IOSetup() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  int n, x; cin >> n >> x;
  if (n == 1) {
    cout << "B\n";
    return 0;
  }
  vector<int> a(n); REP(i, n) cin >> a[i];
  vector<int> l(n, 0), r(n, 0);
  REP(i, n) {
    int sum = a[i], j = i + 1;
    while (j < n && sum + a[j] <= x) sum += a[j++];
    l[i] = j - i;
  }
  REP(i, n) {
    int sum = a[i], j = i - 1;
    while (j >= 0 && sum + a[j] <= x) sum += a[j--];
    r[i] = i - j;
  }
  vector<vector<int> > dp_l(n, vector<int>(n, 0)), dp_r(n, vector<int>(n, 0));
  FOR(len, 2, n + 1) {
    REP(i, n) {
      int j = i + len - 1;
      if (j >= n) break;
      int chou = min(len - 1, l[i]);
      if (dp_r[i + 1][j] - (i + chou + 1 >= n ? 0 : dp_r[i + chou + 1][j]) != chou) {
        dp_l[i][j] = dp_l[i][j - 1] + 1;
        dp_r[i][j] = dp_r[i + 1][j] + 1;
        continue;
      }
      chou = min(len - 1, r[j]);
      if (dp_l[i][j - 1] - (j - chou - 1 < 0 ? 0 : dp_l[i][j - chou - 1]) != chou) {
        dp_l[i][j] = dp_l[i][j - 1] + 1;
        dp_r[i][j] = dp_r[i + 1][j] + 1;
        continue;
      }
      dp_l[i][j] = dp_l[i][j - 1];
      dp_r[i][j] = dp_r[i + 1][j];
    }
  }
  // REP(i, n) FOR(j, i, n) cout << i << ' ' << j << " : " << dp_r[i][j] << '\n';
  cout << (dp_l[0][n - 1] - dp_l[0][n - 2] == 1 ? "A\n" : "B\n");
  return 0;
}