"""
Problem:
The sum of the squares of the first ten natural numbers is,
1^2 + 2^2 + ... + 10^2 = 385
The square of the sum of the first ten natural numbers is,
(1 + 2 + ... + 10)^2 = 552 = 3025
Hence the difference between the sum of the squares of the first ten natural
numbers and the square of the sum is 3025 − 385 = 2640.
Find the difference between the sum of the squares of the first N natural
numbers and the square of the sum.
"""
def solution(n):
"""Returns the difference between the sum of the squares of the first n
natural numbers and the square of the sum.
>>> solution(10)
2640
>>> solution(15)
13160
>>> solution(20)
41230
>>> solution(50)
1582700
"""
suma = n * (n + 1) / 2
suma **= 2
sumb = n * (n + 1) * (2 * n + 1) / 6
return int(suma - sumb)
if __name__ == "__main__":
print(solution(int(input().strip())))