* 46 pages, 1 figure. This paper is a longer version of the paper
arXiv:1802.09963, v3 of which appeared in part as a 4-page extended abstract
at Conference on Learning Theory (COLT) 2018. This paper studies the problem
in another metric, and makes the appropriate corrections to Theorem 2 in v1
and v2 of arXiv:1802.09963, which was incorrect as stated and removed in v3 Access Paper or Ask Questions