montyhall(1000, 3)
Object {stayWins: "349 34.9%", switchWins: "651 65.1%"}
montyhall(1000, 4)
Object {stayWins: "253 25.3%", switchWins: "384 38.4%"}
montyhall(1000, 5)
Object {stayWins: "202 20.2%", switchWins: "265 26.5%"}