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Score : $100$ points

### Problem Statement

You are given a string $S$ of length exactly $9$ consisting of digits. One but all digits from 0 to 9 appear exactly once in $S$.

Print the only digit missing in $S$.

### Constraints

• $S$ is a string of length $9$ consisting of digits.
• All characters in $S$ are distinct.

### Input

Input is given from Standard Input in the following format:

$S$


### Output

Print the only digit missing in $S$.

### Sample Input 1

023456789


### Sample Output 1

1


The string 023456789 only lacks $1$. Thus, $1$ should be printed.

### Sample Input 2

459230781


### Sample Output 2

6


The string 459230781 only lacks $6$. Thus, $6$ should be printed.

Note that the digits in the string may not appear in increasing order.