Take the full name of a singer who had a 1962 #1 hit with "Breaking Up Is Hard to Do" and the one-word name of a group that had a 1970 #1 hit with "Make It With You," mix all of the letters together, and you can get the two-word name (with a total of 15 letters) of a group that had a 1998 #1 hit with "One Week." Who are these musical artists?