Longest Common Substring, I need your help

Question

https://code.sololearn.com/cv97hv3e7qca

the code in the link above is the one that I have written, and the thing is that I have tried a quite a bit, yet still can't quite figure out the error :TypeError: 'int' object is not callable, in this scenario. I think I have tried, and seems that I need help, so if somebody were to explain what has gone wrong, I will deeply appreciate it! Thanks in advance :D!

Answer 1

longest function is overriding by longest variable

Remember function and variable cannot be same in python