n = int(input())
total = 0
k_max = (n + 2) // 3
for k in range(1, k_max + 1):
    a = 3 * k - 2
    total += a
    b = 3 * k - 1
    if b <= n:
        total += b * b
    c = 3 * k
    if c <= n:
        total += c * c * c
print(total)