# Kelvin Ly
# 10/16/12
# Sums up the first N even integers.

def main():
	
	n = int(input("Enter a positive integer.\n"))

	#There are actually two rather elegant solutions, so I'll provide both.

	sum = 0
	for i in range(1,n+1):
		sum = sum + 2*i #This is one of the even integers.

#	sum = 0
#	for i in range(1, 2*n+1):	#The first N integers will be in the first 2N
				#numbers.
#		if i % 2 == 0:		#If it's even,
#			sum = sum + i	#add it to the sum.


#	Yet another solution, without a for loop and more math. You're not
#	likely to come up with this one:
#	sum = n*(n-1)

	print("The sum of the first ", n, " even integers is ", sum, ".",sep="")

main()