Ilya and Sleep disorder

Ilya lives in the beautiful city of Bytes lying in a hilly terrain. She loves to ride her bicycle on the hills whenever she gets a chance to do so. There are check-posts located on the hill at a unit distance from each other. The height of the check posts is given in an array A. Ilya has to visit her aunt who lives N check-posts away. Being a hilly area, the terrain in between the check-posts i