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

Example Input: oHoJrr, YAoJSq
Example Output: oJ

Example Input: VRamNL, mUamIB
Example Output: am

Example Input: EQwkFGewbSSlxhEEahkKVt, rBvaFGewbSSlxhUHOieu
Example Output:
FGewbSSlxh