i think these one car can't came from south,
because point #4 is most southern. There is no
point to the south of a point number 4.

please explain me sample input, i don't understand

The point 4 is 2nd row 6 column.
One car comes from Sount point 3 (2nd row 3 column).
Cars from point 1 and 2 can't get 4point.