import java.math.BigDecimal
import java.math.MathContext

fun main(args : Array<String>) {
    val result = Begginer20190928A.exec(readLine()!!.toInt())
    println(result)
}


object Begginer20190928A {
    fun exec(input : Int) : String {
        val isOdd = input % 2 == 1

        val oddCount = if (isOdd) {
            (input - 1) / 2 + 1
        } else {
            (input) / 2
        }

        return BigDecimal(oddCount)
                .divide(BigDecimal(input), MathContext(10))
                .toString()
    }
}