I saw the manual.
random(a), goes from 0 to a without choosing a.
random(a,b), goes from a to b including a.
What I need in random(a,b) including both a and b.
random(0,1) or random(1)
Goes from 0 to 1 including both 0 and 1 in its selection.
Edit: Changed the title to make it much more clear.