HDU 2009 求数列的和

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