import java.util.Scanner;

public class duishu {
	public static void main(String args[]) {
	double x,k=1,f=1,e,n,a=0;
	Scanner sc = new Scanner(System.in);
	x=sc.nextDouble();
	n=sc.nextDouble();
    if(n < 0)
    System.out.println("error");
    else
    {
    for(int i = 1;i <= n;i++)
    {
    	
        a =Math.pow((double)x,(double)i);
        k = k*i;
        e = a/k;
        f += e;
    }
    System.out.println((double)f);
    }
	}

}