CAN YOU CRACK THIS?????

You are standing in front of a river, you are given two empty bottles, one of 3litters and the other of 5litters and you are asked to put exactly 4litters in the bottle of 5litters by playing around.

PS: The bottles you are given have no measurement, so the only way you can know is to fill up whatever you decide to use.

Go for it and let me know how it went...lol