Answer 1

hi both @paladugu , @Porf. ,
I amended a bit the code, now it creates the file first, and then reads and looks up for an element from the matrix.
it works here at SoloLearn! (it is educational).

https://code.sololearn.com/cf908lYP3efg/?ref=app

Answer 2

Ok, I fixed the code. It works correctly for me.

https://code.sololearn.com/cxxL8s8GFYSE/?ref=app

Answer 3

Good work @yuri! I didn't know that SoloLearn supports creating and saving files.

Answer 4

@Porf, SL does support writing to a file during a session, you cannot save the file permanently.

Answer 5

I missed that it should be read from a file. I'll post later the correct code.