import java.util.*;
import java.io.*;
public class Main {
    public static void main(String[]args){
		Scanner sc = new Scanner(System.in);
		PrintWriter ou = new PrintWriter(System.out);
		int n = sc.nextInt();
		double yono = 0;
		for(int i = 1 ; i <= 20 ; i++){
			yono += Math.sin(i * n) / (long)Math.pow(i , i);
		}
		ou.println(yono);
		ou.flush();
	}
}