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

Q: QRPOwtZATjDoJDdRNNSOH, wiafFMwpAjDoJDdRNNuCDZ

A: jDoJDdRNN
****
Q: yITbYie, TlqTbYomH

A: TbY
****
Q: omSrDtry, IurDthvy

A:
rDt
****