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)

open Batteries
let () =
  let n = Scanf.scanf "%d " (fun a -> a) in

  let rec digits base n res =
    if n = 0 then res 
    else digits base (n/base) ((n mod base)::res)
  in

  Printf.printf "%d\n" @@
    List.fold_left (+) 0 (digits 10 n [])