Problem:
Score : 100 points

Problem Statement

Snuke has a grid consisting of three squares numbered 1, 2 and 3.
In each square, either 0 or 1 is written. The number written in Square i is s_i.

Snuke will place a marble on each square that says 1.
Find the number of squares on which Snuke will place a marble.

Constraints

Each of s_1, s_2 and s_3 is either 1 or 0.

Input

Input is given from Standard Input in the following format:

s_{1}s_{2}s_{3}

Output

Print the answer.

Sample Input 1

101

Sample Output 1

2

A marble will be placed on Square 1 and 3.

Sample Input 2

000

Sample Output 2

0

No marble will be placed on any square.

Solution in OCaml (4.02.3) (judge verdict: Accepted)

let count target s =
  let rec f i tmp =
    if i = String.length s then tmp
    else if s.[i] = target then f (i + 1) (tmp + 1)
    else f (i + 1) tmp
  in
  f 0 0


let () = Scanf.scanf "%s" (fun s -> s) 
         |> count '1' |> Printf.printf "%d\n"