Formula to determine highest number

Hi,
In cell a1 there is the number 50, in cell b1 there is the number 44,
in cell c1 there is the number 8. Here's what I would like to do:
subtract 1/2 of c1 from a1 and 1/2 half of c1 from b1 and place the
highest result in cell d1, i.e. 50-4=46, 44-4=40, then 46 would be
placed in cell d1.
Thanks for your help.
WAB

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