According to my calculations it is 347 light years away.
347 light years, 42 miles, 9 feet, and 3/4 inches, to be precise. I double checked it.
Of course if we were to use Martian years it would be a lot less since the Martian year is 1.88 of our years (687 days). Mars is tilted 25 degrees but I don't know which star would be the North Star on Mars--chances are it is not Polaris. So the Martians probably could care less how far away Polaris is. Anyway they must be hiding way under the surface since our spaceships have yet to find them.