How to assign the sequence for the list?

[Eric]

Does anyone have any suggestions on how to assign the sequence number for a
list?
For example, there is a list of number under column J and M.
[J] [M]
11:00 15
14:45 15
16:00 15
10:30 15
15:30 30
11:00 30
15:00 60

I would like to assign the sequence numbers under column N,
Lower number would be assigned for earlier time, if both times are same,
then I would assign lower number with smaller number under column M.
There is the result as shown below
[J] [M] [N]
11:00 15 2
14:45 15 4
16:00 15 7
10:30 15 1
15:30 30 6
11:00 30 3
15:00 60 5

Does anyone have any suggestions on how to do it under Excel?
Thanks in advance for any suggestions
Eric

 

[Eduardo]

Hi,
You can sort the information by column J