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

Ex Input:
HLtkkRnWkgIdqbQH, dWeFUtkkRnWkgIdZhlQh

Ex Output:
tkkRnWkgId


Ex Input:
UmYbssMbmsXkKQuzNasLOib, EMqlbmsXkKQuzNcyHrpZXOQW

Ex Output:
bmsXkKQuzN


Ex Input:
BoDLavYgptguvopn, KoswoGxLavYgptWxaSq

Ex Output:

LavYgpt