import scala.io.StdIn.*



@main def main =
  val n = readLine().toInt
  val cell = readLine().split(' ').map(_.toInt)
  var last = n - 1
  var result = 0L
  for i <- n - 2 to 0 by -1 do
    if cell(i) == cell(i + 1) then
      last = i + 1
    if cell(i) == 1 then
      result += last - i
  println(result)