How can detect specific lines on the image?

Hi, I'm sorry to ask such silly questions. I am a student who just started studying matlab. I want to detect the line in the 2 images below, and count the number of lines. the purpose of line detection is to compare the number of lines detected in those two images.

To detect the edges, I apply 'Canny' method. and to count the number of edges(I mean, object) I use 'regionprops' function ...

But what I want is the number of straight lines(ex:see red arrows) in the image below

I haven't been able to move on for days. please help me,, T^T Thank you.