Need assistance on Converting a Military to Standard Time.

I have the code below: However, it gives me error ORA-01850

```
select to_char (to_date(tst_time, 'HH24MI'), 'HH:MI AM')  integer_time  FROM STATUS_HISTORY
where tst_id = '75344'

```

I'm thinking that its because the value on tst\_time only has 3 characters for the first 2 entry. How can I add 0 on the beginning of the tst\_time if it contains only 3 numbers?

```
Table Value   Expected Result

TST_Time  integer_time

958      09:58 AM     
541      05:41 AM
1609     04:09 PM

```