Jawaban saya ini, jangan copas

//INGAT YA BRO... MBAK... JANGAN COPY PASTE... UBAH SIKIT KEK
//Soal No.1
import java.io.*;
import java.util.Scanner;

public class Solution {

    public static void main(String args[])
 {
        long a1,a2,n;
        Scanner in = new Scanner(System.in);
        a1 = in.nextInt();
        a2 = in.nextInt();
        n = in.nextInt();
        if(a1==a2)
            {}
        else
            {
            a2=a2-a1;
            n= a1+((n-1)*a2);
            System.out.println(n);
            }
     }
}
//Soal No.2
import java.util.Scanner;
import java.lang.Math;
public class Solution
{
    public static void main(String args[])
    {
        double radius;
        double volume;
        double diameter;

        Scanner masuk = new Scanner(System.in);
        diameter = masuk.nextDouble();
        radius = diameter / 2d;

        volume = (4d / 3)*Math.PI * Math.pow(radius, 3);
        System.out.println(volume);
    }
}
//Soal No.3
BONUS CUK