public class X {

    public class X1 {
        public void method() {}
    }

    public class Y1 {
        public class X2 {
            public void method() {}
        }

        public X2 x;
    }

    public class Z1 {
        public class Y2 {
            public class X3 {
                public void method() {}
            }

            public X3 x;
        }

        public Y2 y;
    }

    public X1 x;
    public Y1 y;
    public Z1 z;

    public void method() {}

}

public class Main {

    private X x;

    public Main() {
        x = new X();
    }

    public void x() {
        x.method();
    }

    public void x_x() {
        x.x.method();
    }

    public void x_y_x() {
        x.y.x.method();
    }

    public void x_z_y_x() {
        x.z.y.x.method();
    }

}