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

SOLUTION: Fyh

PROBLEM: SIIPePlrkftKkzfgdjg, JqNnXHrkftKkzOMUwmc

SOLUTION: rkftKkz

PROBLEM: zqRbqwgmqGIAGTeeoGFOSr, RFnLqwgmqGIAGLcEvAWxY

SOLUTION:
qwgmqGIAG