Questions on the subject "Informatics" how do I make a program?

Question

Robotics

The situation is this:
Rover is somewhere
in the maze. This is a rectangle
in which there are only horizontal walls with passages. The rover needs to be
in the upper left cell
and paint it (and only it) - this is a signal that he has passed the maze.
So I made a function, but I need to make it end at the top point on the top left and paint it. I don't know how to do this.
Please tell me.
And there are 8 more hidden sites, so the formula needs to be made universal for all sites.