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 Python (3.4.3) (judge verdict: Accepted)

#abcをa b c
s = [0,0,0]
n = int(input())
s[0] = n // 100
s[1] = n // 10 - 10 * s[0]
s[2] = n % 10
m = 0
for a in range(3):
    if s[a] == 1:
        m += 1
print(m)