import java.io.BufferedReader;
import java.io.InputStreamReader;

public class soru1 {

	
	public double fact(double F)
	{
		double i=0.;
		double res=1.,tmp=1.;
		
		while(i<F){						
			res=res*tmp;
			tmp=tmp+1.;
			i++;
			//System.out.println(res+" "+i+" "+F+" "+tmp);
		}
		return res;
	}
	public double coz(int X,int N)
	{
		double defP=2.;
		double defF=2.;
		double defC=1.;		
		double sum=0.;
		double res=0.;
		for(int i=0;i<N;i++)
		{
			res=fact(defF);
			//System.out.println("res : "+res);
			if(i%2==0)
				sum+=(Math.pow(X,defP)-defC)/res;
			else
				sum+=(Math.pow(X,defP)+defC)/res;
			//System.out.println(sum+" "+defP+" "+defC+" "+defF);
			defP+=1.;
			defC+=1.;
			defF+=1.;
			
		}
		return sum;
	}
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		System.out.println("X değerini giriniz : ");
		int X=1,N=1;
		try{
		X=Integer.parseInt(br.readLine());
		System.out.println("N değerini giriniz : ");
		N=Integer.parseInt(br.readLine());
		}catch(Exception ex)
		{
			
		}
		soru1 s=new soru1();
		double res = s.coz(X,N);
		System.out.println("res : "+res);
	}

}

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.util.*;

public class soru2 extends Applet implements MouseListener, KeyListener  {

	int X=50;
	int Y=50;
	char ch=' ';
	Point koor;
	int sayac=0;
	Vector v=new Vector();

	
	public void init()
	{
		setBackground(Color.WHITE);
		addMouseListener(this);
		addKeyListener(this);
	}
	
	
	public void paint(Graphics g)
	{
		if(ch == 'c')
		{			
			v.clear();
			ch=' ';
		}
		else{
			for(int i=0;i<v.size();i++)
			{
			 X=((veri)v.elementAt(i)).X;
			 Y=((veri)v.elementAt(i)).Y;
			 g.drawString("ucgen sayısı :"+sayac,0,20);
			 g.drawLine(X,Y,X+30,Y);		
			 g.drawLine(X,Y,X,Y+30);
			 g.drawLine(X+30,Y,X,Y+30);
			}
		}
	}
	public void mouseClicked(MouseEvent arg0) {
		// TODO Auto-generated method stub

	}

	public void mousePressed(MouseEvent arg0) {
		// TODO Auto-generated method stub
		koor=arg0.getPoint();		
		sayac++;
		v.add(new veri(koor));
		repaint();
	}

	public void mouseReleased(MouseEvent arg0) {
		// TODO Auto-generated method stub
		
	}

	public void mouseEntered(MouseEvent arg0) {
		// TODO Auto-generated method stub
		
	}

	public void mouseExited(MouseEvent arg0) {
		// TODO Auto-generated method stub
		
	}


	public void keyTyped(KeyEvent arg0) {
		// TODO Auto-generated method stub
		ch=arg0.getKeyChar();		
		repaint();
	}


	public void keyPressed(KeyEvent arg0) {
		// TODO Auto-generated method stub

	}


	public void keyReleased(KeyEvent arg0) {
		// TODO Auto-generated method stub
		
	}

}

class veri {


	int X;
	int Y;
	public veri(Point p)
	{
		X=p.x;
		Y=p.y;
	}
}