杭电 2009 ( 求数列的和 ) java

import java.util.Scanner;import java.text.DecimalFormat;public class Main {     public static void main(String[] args) {                Scanner sc=new Scanner(System.in);        while(sc.hasNext()){        double n=sc.nextDouble();        int m=sc.nextInt();        int i=1;        double sum=0;               for(int j=0;j<m;j++)        {            sum=sum+n;            n=Math.sqrt(n);                }  DecimalFormat df2=new DecimalFormat("##.00");                              System.out.println(df2.format(sum));        }    }    }