BCD Number Conversion Fix

Problem Description

A BCD number uses one byte to represent a two-digit decimal number, with each group of four bits representing one digit. If a BCD number's hexadecimal is 0x12, it represents the decimal number 12. Xiao Ming mistakenly treated all BCD numbers as binary numbers and converted them to decimal for output; for example, the BCD 0x12 was output as the decimal number 18. Your program should read this wrong decimal number and output the correct decimal number.

Input Format

A single line gives a positive integer in the range $[0, 153]$, guaranteed to be convertible back to a valid BCD number — that is, when this integer is converted to hexadecimal, no A–F digits will appear.

Output Format

Output the corresponding correct decimal number.

Sample Input 1

18

Sample Output 1

12

Sample Input 2

0

Sample Output 2

0

Sample Input 3

153

Sample Output 3

99

Constraints

The input integer is in the range $0 \le n \le 153$.

Hint

• The hard part of this problem is understanding the statement: one byte holds two decimal digits (each taking 4 bits), so valid BCD numbers have an upper bound on the wrong value that gets printed — what is it?
• To fix it, split the wrong value you read into two halves as if in hexadecimal (base 16), then reassemble them as decimal — / and % each handle one half.
• Check against the samples: 18 → 12; 153 → 99.