# frozen_string_literal: true
# This file is expanded by nanacl.

main = -> do # =================================================================
# 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 }
has_one_tally = Hash.new { |h, k| h[k] = 0 }
res = 0
in_a.each do |a|
  tally[a] += 1
  has_one_tally[a] += tally[a - in_d]

  res += has_one_tally[a - in_d]
end
puts res

end # --------------------------------------------------------------------------

# ==============================================================================

main.call