TASK DEFINITION: In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
PROBLEM: xtCJGe, DXCJSw

SOLUTION: CJ

PROBLEM: jinzsW, SMnzaW

SOLUTION: nz

PROBLEM: sYWxbLDcWRGN, oCnhjxbLDcWaUgv

SOLUTION:
xbLDcW