HDU2009 求数列的和

#include <iostream>
#include <cmath>
#include <cstdio>

using namespace std;
int main()
{

	double n;
	int m;
	while(cin >> n >> m)
	{
		double sum = 0;
		while(m--)
		{
			sum += n;
			n = sqrt(n);
		}
		printf("%.2f\n", sum);
	}
	return 0;
}