Assuming LinkedIn used SHA1 unsalted passwords and will continue to do so, and many of us do not want to delete our LinkedIn accounts, what should be the minimu

Assuming LinkedIn used SHA1 unsalted passwords and will continue to do so, and many of us do not want to delete our LinkedIn accounts, what should be the minimum number of characters we should use in our new password? 15? 20? 100? (I know, 100 is probably higher than they allow)