Strange Counter

problem

Bob has a strange counter. At the first second, , it displays the number . At each subsequent second, the number displayed by the counter decrements by .

The counter counts down in cycles. In the second after the counter counts down to , the number becomes  the initial number for that countdown cycle and then continues counting down from the new initial number in a new cycle. The diagram below shows the counter values for each time  in the first three cycles:

https://s3.amazonaws.com/hr-challenge-images/22185/1469447349-bae87a5071-strange1.png

Given a time, , find and print the value displayed by the counter at time .

Input Format

A single integer denoting the value of .

Constraints

Subtask

 for  of the maximum score.
Output Format

Print the value displayed by the strange counter at the given time .

Sample Input

4
Sample Output

6

solution

#!/bin/ruby

t = gets.strip.to_i - 1

s = 3

while s <= t
  t -= s
  s *= 2
end

puts s - t