import math
import sys
def S(): return sys.stdin.readline().rstrip()
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int, sys.stdin.readline().rstrip().split())
def LI(): return list(map(int, sys.stdin.readline().rstrip().split()))
def LS(): return list(sys.stdin.readline().rstrip().split())

d = I()
if d < 4:
    print(0)
elif d%4 == 0:
    print((d//4)**2)
elif d%4 == 1:
    print(((d-1)//4)**2)
elif d%4 == 2:
    print(((d-2)//4)*((d-2)//4+1))
elif d%4 == 3:
    print(((d-3)//4)*((d-3)//4+1))