instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
plSfJAktMfac, TCjYJAktlt
answer:
JAkt


question:
jyJrDIhxJtWbnooEXZ, uyXifNCIhxJtWbnVCUrt
answer:
IhxJtWbn


question:
qxMroOmRlVcuZYx, PLJwhNmRlVcuZsbaEwVj
answer:

mRlVcuZ