package Yukicoder /** * Created by hichikawa on 2015/11/12. */ fun main(args: Array) { fun readLineLongArray(): List { 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 { val str = readLine() as String val arrStr = str.split(" ") val ret = arrStr.map { it.toInt() } return ret } fun readLineDoubleArray(): List { val str = readLine() as String val arrStr = str.split(" ") val ret = arrStr.map { it.toDouble() } return ret } val num = readLineLong() + 2 if (num % 2 == 0.toLong()) { println((num/2)*(num/2)-1) } else { println((num/2)*(num/2+1)-1) } }