#!/bin/python3

import sys


if __name__ == "__main__":
    list1=[]
    sum1=0
    sum2=0
    k = int(input().strip())
    for i in range(1, 1000000, 2):
        list1.append(i)
    for i in range(0,k):
        sum1=sum1+i
    for i in range(0,k):
        sum2=sum2+list1[sum1+i]
    print(sum2)