import random

DELTA = 2

def average(lst):
    return sum(lst)/len(lst)

def backaverage_brute(N, av):
    low = int(av/DELTA)
    high = int(av + (av - av/DELTA))
    c = 0
    while True:
        c += 1
        res = [random.randint(low, high) for i in xrange(N)]
        new_av = average(res)
        if av == new_av:
            return res, c

if __name__ == '__main__':
    res = backaverage_brute(N=100, av=100)
    print 'cycles: ', res[1]
    print res
    print 'average: ', average(res[0])

N = int(open("input.txt").read())
if (N >= 4 and N % 2 == 0):
    list = []
    half = N/2
    halfm = half-1
    for x in xrange(1, halfm):
        if x <= halfm:
            list.append(x*(half-x))
    list.sort()
    open("output.txt", "w").write(str(list[-1]))
else:
    print "susee\n"

for x in N[1:-2]