HELP ME - I read all topics about "conv_forward"

I can send my code - Can you help me??? - I don’t know what to do in Exercise 3

It looks like the problem is that you are not correctly handling each “sample” individually. The “samples” index is the first index of the 4. There are a total of 4 nested loops, right? The outer loop is over the samples. So the logic of the outer loop is that you select the appropriate value of the first index, which should then result in a 3D array instead of a 4D array.

Thanks, but I’ve already did it.
The main problem was that I wrote A_prev instead of a_prev_pad (in the last piece of code).
Other examples of code help me a little.
There are no Zeroes as indexes in code.
Use stride twice - in n_H, n_W and in vert_start, vert_end and horiz_start, horiz_end.
I understand all concept at about 70% and that’s why I spent 3 hours to understand all possible variants how to write pieces of code here to probably find a solution.
Thanks too.