// single file named A.java keeps generating compilation errors, WHY?

class T {

    int x =1, y=2;

    // System.out.println("T class ending: x= " +x+ ", y=" +y); WHY IS THIS AN ERROR?

}

class S extends T { 

    int m = 10;

    int n = m + x +y;

    // System.out.println("S subclass ending: m = " + m + ", n=" + n); WHY IS THIS AN ERROR?

}

public class A{

    public static void main(String[] arg) {

    System.out.println("Program start");

    S s1 = new S();

    System.out.println(s1.m);

    System.out.println(s1.n);

    System.out.println("Program ending");

    }

}