#include<bits/stdc++.h> using namespace std; int main() { double i,m,s; cin>>i>>m; s=ii-mm; s=s*3.14; printf("%.2f",s); return 0; }

#include<bits/stdc++.h>
using namespace std;

int main(){
	int r1,r2;
	double s,pi = 3.14;
	cin>>r1>>r2;
	s = pi * r1 * r1 - pi * r2 * r2;
	cout<<fixed<<setprecision(2)<<s<<endl; 
	 
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()  
{  
double i,m,s;
cin>>i>>m;
s=i*i-m*m;
s=s*3.14;
printf("%.2f",s);
    return 0;  
}