open System
open System.Text.RegularExpressions

let S = Console.ReadLine()

let reg = Regex("(\d)")

match reg.IsMatch(S) with
| false -> 0
| true  -> 
    let mutable sum = 0
    for m in reg.Matches(S) do
      sum <- sum + (m.Groups.[1].Value |> int)

    sum
|> Console.WriteLine