HDOJ 2009 求数列的和

#include<iostream>
#include<cmath>

using namespace std;

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