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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:

$s_{1}s_{2}s_{3}$


### 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.