import java.util.*;
class D
{
public static void main(string args[])
}
int a[]=new int[5];
int b[]=new int[5];
Scanner kb=new Sacnner(System.in;
for(intcj=0;j<=2;j++)
{
a[j]=kb.nextInt();
for(int k=0;k<=2;k++)
}
b[k]=kb.nextInt();
}
int r1=a[2];
int r2=a[2];
double x=3.14*(double)r1*r1;  
double y=3.14*(double)r2*r2;
double sum=x+y;
double ans=(1.813/sum)*100;
System.out.printf("%.2f",ans);