In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.

[Q]: sEYtoQlG, XIstoQQPw
[A]: toQ


[Q]: nhGinCtvLartcMPhJwGRbpZNrq, iQJlFKayEartcMPhJwDRROB
[A]: artcMPhJw


[Q]: DnRCPJPMtKiBuPasb, PYZwPMtKiBiu
[A]:
PMtKiB