# frozen_string_literal: true

def solve
  A.map
   .with_index
   .select { |a, _| a.zero? }
   .map { |_, i| i }
   .tap { _1.unshift(-1) }
   .each_cons(2)
   .map { |prev, now| (now - prev) * (N - now) }
   .sum
end

N = gets.to_i
A = gets.split.map { _1.to_i }

puts solve