instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
gWMyioGBRpwcXfr, AOQGBRpwcSccqBE
answer:
GBRpwc


question:
JIOKyo, oPOKsX
answer:
OK


question:
MFTjWs, LMTjGW
answer:

Tj