SQL & PL/SQL :: Order By Alphanumeric?

create table x(
sno varchar2(5)
);

insert into x values('A-1');
insert into x values('B-1');
insert into x values('B-2');
insert into x values('B-3');
insert into x values('1');
insert into x values('A-2');
insert into x values('2');
insert into x values('3');
insert into x values('A-4');
insert into x values('B-4');
insert into x values('C-4');
insert into x values('D-4');

SQL>select * from x;

SNO
-----
A-1
B-1
1
A-2
2
3
A-4
B-4
C-4
D-4
B-2
B-3

How can I select it ike this

1
A-1
A-2
A-4
B-1
2
B-2
3
B-3
B-4
C-4
D-4