from math import floor, ceil



n = int(eval(input()))

a = n // 2

b = n - a

print((a * b))
from sys import stdin,stdout



def main():

    line=stdin.readline()

    parts=line.split()

    a=int(parts[0])

    par=int(a/2)

    impar=int(a/2)+a%2

    stdout.write(str(par*impar))

main()
from math import floor, ceil

n = int(eval(input()))
a = n // 2
b = n - a
print((a * b))

from sys import stdin, stdout


def main():
    line = stdin.readline()
    parts = line.split()
    a = int(parts[0])
    par = int(a / 2)
    impar = int(a / 2) + a % 2
    stdout.write(str(par * impar))


main()

-from math import floor, ceil +from sys import stdin, stdout -n = int(eval(input())) -a = n // 2 -b = n - a -print((a * b)) + +def main(): +    line = stdin.readline() +    parts = line.split() +    a = int(parts[0]) +    par = int(a / 2) +    impar = int(a / 2) + a % 2 +    stdout.write(str(par * impar)) + + +main()