package main

import (
        "bufio"
        "fmt"
        "os"
        "strconv"
)

func main() {
        N := nextInt()
        N /= 2
        ans := 0
        if N%2 == 1 {
                ans = (N / 2) * (N/2 + 1)
        } else {
                ans = (N / 2) * (N / 2)
        }
        fmt.Println(ans)
}

var sc = bufio.NewScanner(os.Stdin)

func nextInt() int {
        sc.Split(bufio.ScanWords)
        sc.Scan()
        i, e := strconv.Atoi(sc.Text())
        if e != nil {
                panic(e)
        }
        return i
}

func nextString() string {
        sc.Split(bufio.ScanWords)
        sc.Scan()
        return sc.Text()
}