Startup Idea : Live parking spots on streets

I am a driver that struggles to find a parking spot in the city. Sometimes I have to wait few minutes before someone leaves so I can park. Sometimes I see an empty spot but other drives comes and park before me. I was thinking of an app that allows the driver that is leaving to simply click and it will show in a map a red dot, meaning that is an empty spot. The driver that is looking for a parking spot then can come and park there.