# frozen_string_literal: true
in_n, in_d = gets.chomp.split.map(&:to_i)
in_a = gets.chomp.split.map(&:to_i)

tally = Hash.new { |h, k| h[k] = 0}
res = 0
in_a.each do |a|
  tally[a] += 1

  res += tally[a-in_d] * tally[a-in_d*2]
end
puts res