#!/bin/python

import sys

def sumOfGroup(k):
    # Return the sum of the elements of the k'th group.
    num= k*k;
    sum=0
    if k%2==0:
        for i in range(1,k+1,2):
            sum+=num-i + num + i
    else:
        sum=num
        for i in range(2,k,2):
            sum+=num-i+ num+i
        
    return sum        

if __name__ == "__main__":
    k = int(raw_input().strip())
    answer = sumOfGroup(k)
    print answer