Measuring Four Units with a 3-Jug and a 5-Jug

You have an unlimited water supply, a 3-unit jug, and a 5-unit jug, both unmarked. The only operations allowed are: fill a jug completely from the supply, empty a jug onto the ground, or pour from one jug into the other until the source is empty or the destination is full. What is the minimum number of such operations needed to end with exactly 4 units of water in a jug?