let n = stdin.ReadLine() |> int
let a = stdin.ReadLine().Split()

let mutable x = 0L
let mutable result = 0L
for i = 0 to n - 1 do
    if a.[i] = "1" then
        x <- x + 1L
    else
        result <- result + int64 (n - i) * (x + 1L)
        x <- 0L

result
|> printfn "%d"