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 Perl (v5.18.2) (judge verdict: Accepted)

use strict;
use warnings;

main();

sub main {
	my $in = <STDIN>;
	my $out = 0;

	$out += int($in/100);
	$in  -= 100*int($in/100);
   	$out += int($in/10);
	$in  -= 10*int($in/10);
   	$out += $in;
	
	printf("%d\n",$out);

	1;
}