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Interesting Numbers

Given an integer n, determine how many integers x (where 1 ≤ x ≤ n) are interesting. An integer x is considered interesting if the sum of its digits decreases when incremented by 1, i.e., S(x+1) < S(x), where S(x) represents the sum of the digits of x in the decimal system.

Your task is to count how many such interesting numbers exist within the given range.

Example 1

Input:

9

Output:

1

Example 2

Input:

19

Output:

2

Example 3

Input:

1

Output:

0
main.cpp

main.cpp

C++

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