import sys
import math

d = int(input())
if d < 4:
    print(0)
    sys.exit()
    
if d % 2 == 1:
    d -= 1

x = d % 4
d += x

if x == 0:
    ans = pow(d / 4,2)
else:
    ans = (d / 4) * ((d / 4) - 1)

print(int(ans))