import java.text.DecimalFormat;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
@SuppressWarnings("resource")
Scanner in = new Scanner(System.in);
while(in.hasNext()) {
int n = in.nextInt();
int m = in.nextInt();
if (n<10000 && m<1000) {
SequenceSum(n,m);
}else {
continue;
}
}
}
public static void SequenceSum(int n, int m) {
double sum = n;
double temp = Math.sqrt(n);
for(int i=1;i<m;i++) {
sum = sum + temp;
temp = Math.sqrt(temp);
}
DecimalFormat df = new DecimalFormat("#.00");
System.out.println(df.format(sum));
}
}