#!/bin/python3

import sys

def sumOfGroup(k):
    # Return the sum of the elements of the k'th group.    
    sum_of_pa = int(k * (k + 1)/2)
    sum = 0
    for temp in range(k):
        sum += ((sum_of_pa * 2)-1 )-(temp * 2)
    return sum

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