Consider a company that owns N apple farms and wants to find an optimal picking schedule over M days. Farm i is predicted to have aij apples available for picking on day j. The company wants to meet a demand of dj apples for day j. But capacity limitations force the company to only pick up to uj apples on day j. Apples picked on any day can be stored and used to satisfy demand on later days, but there is a storage cost of cj for storing an apple at the end of day j. We also assume that apples that are available (but not picked) on day j are available on subsequent days. Formulate the problem of determining a minimum-cost apple-picking schedule as a minimum cost Network Flow problem. (It is enough for you to explain the structure of the network; you do not have to write down a linear programming formulation.)