Excel 2007 : Calculating Time diifference in different Buckets

Hi,
Can somebody help in solving the attached Excel, where i want to bucketize the Minutes in various buckets.
Eg: If Start Time is 17:00:00 and End time is 23:00:00 and i have 2 Buckets (1200 Hrs to 1800 Hrs & 1800 Hrs to 0000Hrs); then the result should come as:

Bucket (1200 Hrs to 1800 Hrs ) : 60 Mins & Bucket (1800 Hrs to 0000 Hrs ) : 300 Mins.