Marijuana posession

So, the other day I was parked with some friends near a public park. I personally didn't have any marijuana on me and none was found by my seat (driver) when the police searched the car. But my friend had an ounce on him and my other friend (passenger seat) hid about half a gram under his seat which was found. And about another half gram which another of my friends left on the back seat because the police came was found too. My point to all this is that I want to know what is the most that can happen to me (the driver) since I didn't have any on me but some was found in my car?

By the way this happend in Montreal, Canada and this is my first offence ever.