class BinaryIndexTree
  def initialize(size, init: 0)
    @values = Array.new(size, init)
    @size = size
  end

  # @param idx [Integer]
  # @param x [Numeric]
  def add(idx, x)
    raise 'Out of range reference' if @size <= idx

    idx += 1

    while idx <= @size
      @values[idx - 1] += x
      idx += idx & -idx
    end
  end

  def sum(l, r)
    _sum(r) - _sum(l)
  end

  private

  def _sum(idx)
    res = 0

    while idx > 0
      res += @values[idx - 1]
      idx -= idx & -idx
    end

    res
  end
end

class Array
  def inversion_number
    n = size
    bit = BinaryIndexTree.new(n + 1)
    cnt = 0

    n.times do |i|
      cnt += i - bit.sum(0, self[i])
      bit.add(self[i], 1)
    end

    cnt
  end
end


N = gets.to_i
P = gets.split.map(&:to_i)

puts P.inversion_number