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

[Q]: nYoRQU, gQoRZQ
[A]: oR


[Q]: XZslQqrShfCXRXyHrFVq, BtOQgQqrShfCXRRCRbMvXPM
[A]: QqrShfCXR


[Q]: xSSyCNIGFbQqa, GSDRTyCNIGFmaDbcB
[A]:
yCNIGF