#!/bin/python3

import sys

def find_first_k_even(k):
    result1 = 1
    for i in range (1,k) : 
        #result1+=2
        result1 = result1 + i*2
    result2 = 0
    #print("result1", result1)
    for i in range (result1,result1+2*k) : 
        if i % 2 !=0:
            result2 += i
    #print(result2)
    return result2
        
def sumOfGroup(k):
    temp = find_first_k_even(k)
    return temp
    # Return the sum of the elements of the k'th group.

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