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License Software

License Software

As you know, to verify the licensed software used by the serial number and reshistratsionnye keys. You, as a leading developer of verification of license software was developed the idea of reliable in-a-kind system. It Is based on the digital roots of numbers. Now you need to write a program that defines the digital root of this number.

For an arbitrary number of digital root is defined as follows:

  1. If the amount is less than ten-digit number, then the digital root is the sum of digits of that number.
  2. Otherwise, the digital root of a number equal to the digital root of the sum of its digits.


One number n (0n 231- 1).


Print one number - the answer to the challenge.

Time limit 1 second
Memory limit 128 MiB
Input example #1
Output example #1