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

Q: zRwQdelc, UdAUwQdejhe

A: wQde
****
Q: sEYtoQlG, XIstoQQPw

A: toQ
****
Q: ARjVgdRU, sOHVgdcjm

A:
Vgd
****