import sys

sys.setrecursionlimit(10 ** 6)
stdin = sys.stdin

ni = lambda: int(ns())
na = lambda: list(map(int, stdin.readline().split()))
ns = lambda: stdin.readline().strip()
nsa = lambda: list(stdin.readline().split())
mod = 10 * 7 + 7

n = ni() // 2
ans = 0

print(n ** 2)