import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }




void main() {
  try {
    for (; ; ) {
      const N = readInt();
      const X = readLong();
      auto A = new long[N];
      foreach (i; 0 .. N) {
        A[i] = readLong();
      }
      
      auto ASum = new long[N + 1];
      foreach (i; 0 .. N) {
        ASum[i + 1] = ASum[i] + A[i];
      }
      auto ls = new int[N + 1];
      auto rs = new int[N + 1];
      foreach (i; 0 .. N + 1) {
        ls[i] = ASum.upperBound(ASum[i] + X);
        rs[i] = ASum.lowerBound(ASum[i] - X);
      }
      debug {
        writeln("A = ", A);
        writeln("ls = ", ls);
        writeln("rs = ", rs);
      }
      
      auto dp0 = new int[][](N + 1, N + 2);
      auto dp1 = new int[][](N + 1, N + 2);
      bool check0(int i, int ja, int jb) {
        return (dp0[i][jb] - dp0[i][ja] < jb - ja);
      }
      bool check1(int j, int ia, int ib) {
        return (dp1[j][ia] - dp1[j][ib] < ib - ia);
      }
      
      foreach (w; 2 .. N + 1) {
        foreach (i; 0 .. N - w + 1) {
          const j = i + w;
          int x = 0;
          // eat [i, i + 1), ..., [i, ls[i] - 1)
          if (check1(j, i + 1, min(ls[i], j))) {
            x = 1;
          }
          // eat [rs[j], j), ..., [j - 1, j)
          if (check0(i, max(rs[j], i + 1), j)) {
            x = 1;
          }
          debug {
            writeln(i, " ", j, ": ", x);
          }
          dp0[i][j + 1] = dp0[i][j] + x;
          dp1[j][i] = dp1[j][i + 1] + x;
        }
      }
      
      debug {
        auto brt = new int[][](N + 1, N + 1);
        foreach (w; 2 .. N + 1) {
          foreach (i; 0 .. N - w + 1) {
            const j = i + w;
            foreach (k; i + 1 .. j) {
              if (ASum[k] - ASum[i] <= X) {
                if (!brt[k][j]) {
                  brt[i][j] = 1;
                }
              }
            }
            foreach (k; i + 1 .. j) {
              if (ASum[j] - ASum[k] <= X) {
                if (!brt[i][k]) {
                  brt[i][j] = 1;
                }
              }
            }
          }
        }
        foreach (i; 0 .. N + 1) {
          writeln(i, ": ", brt[i][i + 1 .. $]);
        }
        foreach (i; 0 .. N + 1) foreach (j; i + 1 .. N + 1) {
          if (brt[i][j] != dp0[i][j + 1] - dp0[i][j]) {
            writeln(i, " ", j, ": ", brt[i][j], " ", dp0[i][j + 1] - dp0[i][j]);
            assert(false);
          }
        }
      }
      
      const ans = dp0[0][N + 1] - dp0[0][N];
      writeln(ans ? "A" : "B");
    }
  } catch (EOFException e) {
  }
}