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 PHP (5.6.30) (judge verdict: Time Limit Exceeded)

<?php

//----------------------------------------------------------------------------------
// Input
//----------------------------------------------------------------------------------

$sc = new Scanner();
$n = $sc->nextInt();

$a = array();
for ($i = 0; $i < $n; $i++) {
  $a[] = $sc->nextInt();
}

//----------------------------------------------------------------------------------
// Input for test
//----------------------------------------------------------------------------------
/*
$n = 3;
$a = array(16, 16, 16);
*/
//----------------------------------------------------------------------------------
// Main
//----------------------------------------------------------------------------------

$ans = 0;
while (1) {
  for ($i = 0; $i < count($a); $i++) {
    if ($a[$i] % 2 == 1) { break 2; }
    $a[$i] /= 2;
//echo $a[$i]."\n";
  }
  $ans++;
}


//----------------------------------------------------------------------------------
// Output
//----------------------------------------------------------------------------------
out::println($ans);



//----------------------------------------------------------------------------------
// Ref: https://qiita.com/yoshikyoto/items/6924478283dbdd549e4b
//----------------------------------------------------------------------------------
class Scanner {
  private $arr = array();
  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;
  }
}

?>