N = gets.to_i
A = gets.split.map(&:to_i)
all = N * (N + 1) / 2
cnt = 0
cur = 0

A.each do |a|
  if a == 0
    cnt += cur * (cur + 1) / 2
    cur = 0
  else
    cur += 1
  end
end

cnt += cur * (cur + 1) / 2
puts all - cnt