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

mCxQTIaXN, mWQTIaxzPT
QTIa

vFuggVITQuctFG, hdCIWWuuggVITQwr
uggVITQ

fgWHZBavxrBGLrbstMHRQd, kXSZFsRVvxrBGLrbsXhKke

vxrBGLrbs