fun main(args: Array<String>) {
    val N = readLine()!!.toInt()
    val list :List<Int> = listOf()
    val r = odd(N,list)
    val answer :Float = r.size.toFloat()/N.toFloat()
    println(answer)
}

fun odd(n :Int,list :List<Int>) :List<Int> {
    return when (n) {
        1 -> list + listOf(1)
        else -> {
            if (n % 2 == 0) {
                odd(n-1, list)
            } else {
                odd(n-1 , list + listOf(n))
            }
        }
    }
}