#include <stdio.h>
#define PI 3.14
double a(double num);
double b(double num,double num2);
int main(void)
{
double q,w;
scanf("%lf %lf",&q,&w);
printf("result: %lf",b(q,w));
return ;
}
double a(double num)
{
double result = num*num*PI;
return result;
}
double b(double num,double num2)
{
double result = num2*num2*PI - a(num);
if(((int)result < 0))
result = -result;
return result;
}