instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
eJPZzg, lFPZbI
answer:
PZ


question:
yOGvgtAmwMwcIRtJ, cQtAmwMwcIRjfjO
answer:
tAmwMwcIR


question:
VNxPhKKhnF, IrnSoPhKKhjN
answer:

PhKKh