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

//$_input = explode(
//    "\n",
//    '000'
//);

function getNext() {
    return trim(
        isset($GLOBALS['_input'])
            ? array_shift($GLOBALS['_input'])
            : fgets(STDIN)
    );
}

$s = getNext();
$count = count(array_filter(str_split($s), function ($x) {
    return $x === '1';
}));

printf("%d\n", $count);