Problem:
Score : 100 points

Problem Statement

Given is an integer r.

How many times is the area of a circle of radius r larger than the area of a circle of radius 1?

It can be proved that the answer is always an integer under the constraints given.

Constraints

1 \leq r \leq 100

All values in input are integers.

Input

Input is given from Standard Input in the following format:

r

Output

Print the area of a circle of radius r, divided by the area of a circle of radius 1, as an integer.

Sample Input 1

2

Sample Output 1

4

The area of a circle of radius 2 is 4 times larger than the area of a circle of radius 1.

Note that output must be an integer - for example, 4.0 will not be accepted.

Sample Input 2

100

Sample Output 2

10000

Solution in Ruby (2.3.3) (judge verdict: Accepted)

a =  $stdin.read.to_i
#n = 10 ** 5
n = 2

def power2(a, n)
  return 1 if n == 0
  k = power2(a, n >> 1)
  k *= k
  return k if n & 1 == 0
  return k * a
end

sum = 0
(0..n).each{|i|
  #sum += power2(a, i)
  sum = power2(a, i)
}
#sum == a ** (n + 1) / (a - 1)
puts sum.to_i