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

cvZfWOwa, xOfWOhZs
fWO

fWJdaAfOCfejXZvidHM, gOpfOCfejXZbtLvSLZI
fOCfejXZ

yomEdNhiUZdvSK, iqIeSmEdNhiQQi

mEdNhi