#!/bin/python3

import sys

def sumOfGroup(k):
    list_elem = []
    sum = 0
    for x in range(1, (k*(k+1)) + 1):
        if (x%2 !=0):
            list_elem.append(x)
    for count in range(int(k)):
        sum += list_elem[k]
        k += 1
    return sum

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