#!/bin/python

import sys

def sumOfGroup(k, tempSet): 
    prev = 0
    for i in range(0, k):
        prev += i
    #print 2*prev+1
    #for i in tempSet.keys():
    #    if i == k:
     #       return tempSet[k]
    curr = 2*prev + 1
    temp_sum = 0
    for i in range(0, k):
        temp_sum += curr
        curr += 2
    return temp_sum
    # Return the sum of the elements of the k'th group.

if __name__ == "__main__":
    tempSet = {}
    curr = 1
    k = 1
    index = 0
    tempSum = 0
    while(1):
        if curr > 1000000:
            break
        if index < k:
            tempSum += curr
            index+=1
        else:
            index = 1
            tempSet[k] = tempSum
            tempSum = curr
            k+=1
        curr += 2
    k = int(raw_input().strip())
    answer = sumOfGroup(k, tempSet)
    print answer