import java.util.*;
class Main{
public static void main(String args[])
{Scanner cin=new Scanner(System.in);
final double PI=3.1415927;
while(cin.hasNext())
{double a=cin.nextDouble();
double c=4.0*PI*a*a*a/3.0;
System.out.printf("%.3f",c);
System.out.println();
}
}
}
注意要将4/3；转化为4.0/3.0