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

SOLUTION: oR

PROBLEM: YlhtTQgHiffTbIbBrcHMqFKCdWz, HyregFgMffTbIbBrcHYUnnQvGlx

SOLUTION: ffTbIbBrcH

PROBLEM: OQlMSb, mdlMsE

SOLUTION:
lM