#!/bin/python3

import sys

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

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