Motu and Patlu

Patlu wants to make apple pie for Motu. So he goes to the orchid for apples. Now the orchid has apple and mango trees arranged in square matrix of order N. Such that he doesn’t get bored while apple picking, he decides to do it in a pattern. He always starts and end at the boundary cells of the matrix and travels only those paths that has apple trees only. He will cover the entire matrix by moving