question on mergesort

["Harshida Kothari" <harshida@home.com>]

I will really appreciate if you can help me to figure out the worst-case
recurrence relationship for four-way merge sort algorithm.
Four-way merge sort algorithm splits the array into four "equal" parts,
recursively merge sorts each part, and merges the resulting parts together.
And also for an array containing 4^8 elements, what is the largest number of
call-frames for merge sort that will be on run-time stack at the same time?

Thank you.

Harshida
harshida@home.com