Batteries Needed!

The most dangerous cyborg Jenish is finally entrapped on a narrow bridge over a valley. The bridge is $N$ meters long. For convenience, position $i$ represents a portion of bridge between whose left border is at distance $i-1$ meters from left end and right border is at distance $i$ meters from left end. There are $N$ batteries placed at positions $1,2...N$. The $i^{th}$ one has energy $a[i]$.