杭电 hdu 2009

求数列的和：

#include<stdio.h>
#include<cmath>
int main(){
    double n,m;
    while(scanf("%lf %lf",&n,&m)!=EOF){
        double sum=n;
        m--;
        while(m>0){
            n=sqrt(n);
            sum+=n;
            m--;
        }
        printf("%.2lf\n",sum);
    }
    return 0;
}