import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt();
		sc.close();

		long s = System.currentTimeMillis();
		double ans = 0;
		for (int i = 1; System.currentTimeMillis() - s < 1800; i++) {
			ans += Math.sin(k * i) / Math.pow(i, i);
		}
		System.out.println(ans);
	}
}