SAMPLE POST

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
       Scanner sc=new Scanner(System.in);
        int diameter =sc.nextInt();
        int radius = diameter/2;
        int area=(22*radius*radius)/7;
            System.out.print(area);
    }
}