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

JIOKyo, oPOKsX
OK

XZslQqrShfCXRXyHrFVq, BtOQgQqrShfCXRRCRbMvXPM
QqrShfCXR

TuElvadTKBCjVdO, pGwaBdkUxElvadTKBCFESUY

ElvadTKBC