#include <stdio.h>
#include <math.h>
int main() {
    int m = 0;
    double n = 0.00;
    while (~scanf("%lf %d", &n, &m)) 
    {
        double sum = 0;
        int arr[1000] = {0};


        for (int i = 0; i < m; i++) 
        {
            sum = sum + n;
            n = pow(n, 0.5);
            
        }
        printf("%.2f\n", sum);
    }
    return 0;
}