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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;

namespace oasobi
{
    static class MainClass
    {
        public static void Main()
        {
            string s = Console.ReadLine();
            int counter = 0;
            for(int r = 0; r <= 2; r++)
            {
                if (s[r] == '1')
                {
                    ++counter;
                }
            }

            Console.WriteLine(counter);
        }
    }
}