interface variables declarations

package interfaces;
interface IVariable
{
    int x=10;
    public int px=15;
    final int fx=20;
    static int sx=40;
    final static int fsx=50;
    // All above declarations are same.
    // By default interface variables are public static final

     private int pi=60;   //error
     volatile int vx=80;    // error
    
}

public class InterVariable implements IVariable{
    public static void main(String arg[])
    {
                System.out.println(x);  //10
                x=30;   //error
    }
}