Three dice having digits 1,2,3,4,5 and 6 on their faces are marked...

Three dice having digits $1,2,3,4,5$ and 6 on their faces are marked I, II and III and rolled. Let $x, y$ and $z$ represent the number on die $=\mathrm{I}$ die $=\mathrm{II}$ and die -III respectively. What is the number of possible outcomes such that $x > y > z$ ?