Garden Watering

Sufiland is rectangle in shape with dimensions n x 1, It’s length is divided into n equal units of 1 x 1 . Here is the tricky part, each unit is having different height from the ground. Let’s say ith unit is having height hi . Sufi wants to water Sufiland but she is too lazy to do that, So she decided to put all water on a single unit of Sufiland, and let the water flow. Sufi is interested to k