C :

#include<stdio.h>
void main()
{
	int r1,r2;
	double s,p=3.14;
	scanf("%d%d",&r1,&r2);
	s=p*r1*r1-p*r2*r2;
	printf("%.2f",s);
	
}

C++ :

#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;
}

Pascal :

var
        i,j,n,m:integer;
begin
        read(n,m);
        writeln((n*n-m*m)*3.14:0:2);
end.

Java :

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int r1 = sc.nextInt();
		int r2 = sc.nextInt();
		double pi = 3.14;
		double s1,s2,s3;
		s1 = pi * r1 * r1;
		s2 = pi * r2 * r2;
		s3 = s1 - s2;
		System.out.printf("%.2f",s3);
	}
}

Python :

a,b=map(int,input().split())
s=a*a*3.14-b*b*3.14
print('{:.2f}'.format(s))