100810: [AtCoder]ABC081 A - Placing Marbles

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.