package Yukicoder

fun main(args: Array<String>) {
    fun readLineLongArray(): List<Long> {
        val str = readLine() as String
        val arrStr = str.split(" ")
        val ret = arrStr.map { it.toLong() }
        return ret
    }

    fun readLineLong(): Long {
        val str = readLine() as String
        return str.toLong()
    }

    fun readLineInt(): Int {
        val str = readLine() as String
        return str.toInt()
    }

    fun readLineIntArray() : List<Int> {
        val str = readLine() as String
        val arrStr = str.split(" ")
        val ret = arrStr.map { it.toInt() }
        return ret
    }

    fun readLineDoubleArray(): List<Double> {
        val str = readLine() as String
        val arrStr = str.split(" ")
        val ret = arrStr.map { it.toDouble() }
        return ret
    }

    fun readLineDouble() : Double {
        val str = readLine() as String
        return str.toDouble()
    }

    fun readLineString() : String {
        return readLine() as String
    }

//    fun readLineStringArray(): List<String> {
//        val str = readLine() as String
//        val arrStr = str.split(" ")
//        return arrStr
//    }

    val num = readLineLong() / 2
    if (num % 2 == 1.toLong()) {
        println((num/2)*(num/2+1))
    } else {
        println((num/2)*(num/2))
    }

}