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)

#!/usr/bin/env php
<?php
function genInputs() {
    while(($input = rtrim(fgets(STDIN))) !== false) {
        foreach (explode(' ', $input) as $v) {
            yield $v;
        }
    }
}
function getNext($gen) {
    $value = $gen->current();
    $gen->next();
    return $value;
}
$gen = genInputs();

$s = getNext($gen);
$n = 0;
for ($i = 0; $i < strlen($s); $i++) {
    if ($s[$i] == 1) {
        $n++;
    }
}
echo $n.PHP_EOL;