import java.io.InputStream
import java.io.PrintWriter
import java.util.*

fun PrintWriter.solve() = with(FastScanner(System.`in`)) {
    val n = nextInt()
    var ans = 0.0
    for (i in 1 until 1000) {
        ans += Math.pow(1.0 / i, n.toDouble())
    }
    println(ans)
}

fun main() {
    val writer = PrintWriter(System.out, false)
    writer.solve()
    writer.flush()
}

class FastScanner(s: InputStream) {
    private var st = StringTokenizer("")
    private val br = s.bufferedReader()

    fun next(): String {
        while (!st.hasMoreTokens()) st = StringTokenizer(br.readLine())
        return st.nextToken()
    }

    fun nextInt() = next().toInt()
    fun nextLong() = next().toLong()
    fun nextLine() = br.readLine()
    fun nextDouble() = next().toDouble()
}