# Task
 Below we will define what and n-interesting polygon is and your task is to find its area for a given n.
 A 1-interesting polygon is just a square with a side of length 1. An n-interesting polygon is obtained by taking the n - 1-interesting polygon and appending 1-interesting polygons to its rim side by side. You can see the 1-, 2- and 3-interesting polygons in the picture below.
 ![](https://files.gitter.im/myjinxin2015/Gwsw/blob)
# Example
 For `n = 1`, the output should be `1`;
 For `n = 2`, the output should be `5`;
 For `n = 3`, the output should be `13`.
# Input/Output
 - `[input]` integer `n`
    Constraints: `1 ≤ n < 10000.`
 - `[output]` an integer
   The area of the n-interesting polygon.
def shape_area(n):
  p = 0
  area = 1
  for i in range (1, n):
      p = n*4-4
      n -= 1
      area += p
  return area
  

def shape_area(n):
  p = 0
  area = 1
  for i in range (1, n):
      p = n*4-4
      n -= 1
      area += p
  return area
  
