#include <bits/stdc++.h>
#define _rep(i, l, r) for (auto i = (l); i < (r); ++i)
namespace FastIO {
char buf[1 << 21], buf2[1 << 21], a[20], *p1 = buf, *p2 = buf, hh = '\n';
int p, p3 = -1;
int getc() {
  return p1 == p2 &&
             (p2 = (p1 = buf) + fread(buf, 1, 1 << 21, stdin), p1 == p2) ?
           EOF :
           *p1++;
}
void read() {}
void print() {}
template <typename T, typename... T2>
void read(T &x, T2 &...oth) {
  int f = 0;
  x = 0;
  char ch = getc();
  while (!isdigit(ch)) {
    if (ch == '-') f = 1;
    ch = getc();
  }
  while (isdigit(ch)) {
    x = x * 10 + ch - 48;
    ch = getc();
  }
  if (f) x = -x;
  read(oth...);
}
void flush() { fwrite(buf2, 1, p3 + 1, stdout), p3 = -1; }
template <typename T, typename... T2>
void print(T x, T2... oth) {
  if (p3 > 1 << 20) flush();
  if (x < 0) buf2[++p3] = 45, x = -x;
  do { a[++p] = x % 10 + 48; } while (x /= 10);
  do { buf2[++p3] = a[p]; } while (--p);
  buf2[++p3] = hh;
  print(oth...);
}
template <typename T>
void print_h(T x, char h) {
  if (p3 > 1 << 20) flush();
  if (x < 0) buf2[++p3] = 45, x = -x;
  do { a[++p] = x % 10 + 48; } while (x /= 10);
  do { buf2[++p3] = a[p]; } while (--p);
  buf2[++p3] = h;
}
void putchar(char a) { buf2[++p3] = a; }
}  // namespace FastIO
using FastIO::print;
using FastIO::print_h;
using FastIO::read;
const int M = 1 << 16;
const int N = 17;
i64 f[M][N], s[N], n, delta;
int main() {
  read(n, delta);
  _rep(i, 0, n) read(s[i]);
  _rep(i, 0, n) f[1 << i][i] = 1;
  _rep(i, 0, 1 << n) {
    _rep(j, 0, n) {
      if (!(i & (1 << j))) continue;
      _rep(k, 0, n) {
        if (i & (1 << k)) continue;
        if (s[j] - s[k] > delta || s[k] - s[j] > delta)
          f[i | (1 << k)][k] += f[i][j];
      }
    }
  }
  i64 ans = 0;
  _rep(i, 0, n) ans += f[(1 << n) - 1][i];
  print(ans);
ex:
  FastIO::flush();
  return 0;
}