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

SOLUTION: eqnu

PROBLEM: yQCDWefwvrPP, RwoMDWefwhSxTR

SOLUTION: DWefw

PROBLEM: iwSQnplQZFbXQ, lHWnplQZFzswgU

SOLUTION:
nplQZF