#include<stdio.h>
#include<math.h>
int main()
{
int n, m, i;
while (scanf("%d%d", &n, &m) != EOF)
{
double s = n;
double k = n;
for (i = 0; i < m-1; i++)
{
s = s + sqrt(k);
k = sqrt(k);
}
printf("%.2lf\n", s);
}
return 0;
}