i wud like to put this formula in excel,if someone can please guide me,

if c1a1 and if c1b1 then d1=0,
if c1a1 and if c1<b1 then d1=c1-b1
if c1<a1 and if c1<b1 then d1=a1-b1
and
if c1<a1 and c1b1 then d1=a1-c1
--
thanks and
rgds

amit