2018 US group comments spring C ++ exam programming questions-digital characters, 2018 US dollars

2018 US group comments spring C ++ exam programming questions-digital characters, 2018 US dollars

Comments from the US Mission: 2018 online examination for the development direction of the spring recruitment background

Programming question | 30.0 points 2/2

Numeric characters

Time limit:The C/C ++ language is 2000 MS; other languages are 4000 MS.
Memory limit:C/C ++ language 65536KB; other languages 589213kb

Description:

In decimal notation, any positive integer can be expressed with the character '0'-'9. However, when the number of each character of '0'-'9' is limited, some positive integers may not be expressed. For example, if you have two '1' and one '2', you can represent 11,12, 121, and so on, but not 10,122,200.

Now you have some characters in your hand. They are all '0'-'9' characters. You can select some of the characters and combine them into a number. What is the smallest positive integer you cannot constitute?

Input

The first line contains a string consisting of '0'-'9', indicating the characters you can use.

· 1 ≤ string length ≤ 1000.

Output

Output the smallest positive integer that you cannot form.

?

Sample Input

55

Sample output

1

?

Hint

Input Sample 2

123456789

Output Sample 2

10