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 PHP7 (7.0.15) (judge verdict: Accepted)

<?php
$sc = new Scanner();
$a = $sc->next();

$count = 0;
str_replace("1", "", $a, $count);
out::println($count);

class Scanner
{
    private $arr = [];
    private $count = 0;
    private $pointer = 0;

    public function next()
    {
        if ($this->pointer >= $this->count) {
            $str = trim(fgets(STDIN));
            $this->arr = explode(' ', $str);
            $this->count = count($this->arr);
            $this->pointer = 0;
        }
        $result = $this->arr[$this->pointer];
        $this->pointer++;
        return $result;
    }

    public function hasNext()
    {
        return $this->pointer < $this->count;
    }

    public function nextInt()
    {
        return (int)$this->next();
    }

    public function nextDouble()
    {
        return (double)$this->next();
    }
}

class out
{
    public static function println($str = "")
    {
        echo $str . PHP_EOL;
    }
}