import java.io.*;
public class file2
{
public static void main (String [] args) throws IOException
{
double phi=3.14;
double file2 ;
double r;
int i=0;
BufferedReader br;
br=new BufferedReader (new InputStreamReader(System.in));
while (i<4)
{
r=Double.parseDouble(br.readLine());
file2=phi*r*r;
System.out.println("luas lingkaran: " +file2);
i++;
}
}
}