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

JqdTDnZqSuSVcMsx, TEtDDnZqSuZa
DnZqSu

kWnjCoVmCSVuW, RILPKCoVmCSVbaOza
CoVmCSV

vpoQNvKwCGu, AYGNvKwCXqlbh

NvKwC