The task of drunken fishermen.

Good day to all!
This is my first post on Habré. So boldly minus, I'm ready.
So, now I will make you a puzzle, then I often read such things, with pleasure I solve ... The problem is simple, solved in a few minutes, and maybe for the habial community and generally oral, but I’m interested in the most effective way of solving, to see how others think. Yes, yes, it is also possible that this is dupe, you solved it in the second grade, this task is on all sites ... But I have not seen it before, heard and decided only today, and now I am sharing with you.
Actually the task:

Three men went fishing, threw a net, sat for a while and went to bed.
In the morning I woke up first, pulled out the net, counted a fish, threw one back into the river, took a third of what was left and went home.
Then I woke up the second, counted a fish, threw one into the river, took a third and also went home.
Finally, I woke up the third, counted a fish, threw one out, took a third and went home.
Question of the problem - what is the minimum amount of fish men could catch?
And the question from me is the easiest way to solve this problem in your opinion?

PS Maybe the solution is to write white? :)