#!/bin/python3

import sys
odds = []
for i in range(10**6):
        if(i%2 != 0):
            odds.append(i)
            
def sumOfGroup(s,i,k):
    total = 0
    if(i < k):
        s += i
        i += 1
        sumOfGroup(s,i,k)
        
    for i in range(s,s+k):
        total += odds[i]
    return(total)
    

if __name__ == "__main__":
    k = int(input().strip())
    answer = sumOfGroup(0,1,k)
    print(answer)