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.

Input

Input is given from Standard Input in the following format:
S

Output

Print the only digit missing in S.

Constraints

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

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.

见题面 Input 部分

见题面 Output 部分