#!/bin/python3

import sys

def sumOfGroup(k):
    # Return the sum of the elements of the k'th group.
    x= range(1,((10**6)+1),2)
    t=(k*(k+1))/2
    return sum(x[int(t-k):int(t)])
    

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