In sql substract next value from previous value and check

Question

i have data in Log column

Log 

8:50

8:50

9:50

10:00

10:00

10:00

13:00

15:00

when i substract next value from previous value and the difference is greater than 5 min then skip the next value and first value store kip as it is in column

ex suppose we substract 10:00 fom 9:50 and diff is greater than 5 min skip the 10:00 and store 9:50