instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
jinzsW, SMnzaW
answer:
nz


question:
zzEhnt, sYEhtc
answer:
Eh


question:
pseLJnyBcldReDpcy, uCxMPJnyBcldRvWInq
answer:

JnyBcldR