6. Pompous Vova has an iPhone XXX, and on that iPhone there is a voice-command calculator: "Multiply my number by two and subtract two from the result," "Be so kind as to multiply my number by three and then add four," and finally, "Add seven to my number!" The iPhone knows that Vova initially had the number 1. How many four-digit numbers could the iPhone XXX theoretically obtain by obediently following Vova's commands?

## Solution: