instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
sGrHRmELarByxp, cDCUnmELarBXbEfM
answer:
mELarB


question:
GHdeqnuYnQ, zzQeqnutAZ
answer:
eqnu


question:
DCIhXJkbYeGSgC, LnOXJkbYbGyUw
answer:

XJkbY