instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
XMtSwZVAHsNYhbyDm, asAVAHsNYhSPuNLrV
answer:
VAHsNYh


question:
mjCEUoPmeKbvCgUtUL, SrHtrPmeKbvYpQAVp
answer:
PmeKbv


question:
zGsfDAQZXxRtsCfftF, bERHNDcKAQZXxRtsCBsUvo
answer:

AQZXxRtsC