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


let mutable lastZero = -1
[|
    for i in 0..a.Length-1 ->
        if a.[i] = 0 then
            let count = (i - lastZero) * (a.Length-i)
            lastZero <- i
            count
        else
            0
|] |> Array.sum |> printfn "%d"