n, d = read_line.split.map(&.to_i)
a = read_line.split.map(&.to_i)
ans = 0i64
cf = Hash(Int32, Int64).new(0)
cb = Hash(Int32, Int64).new(0)
a.each { |v| cb[v] += 1 }
n.times do |i|
  cb[a[i]] -= 1
  ans += cf[a[i] - d] * cb[a[i] + d]
  cf[a[i]] += 1
end
puts ans