Can someone help me with this problem in optimising? A warehouse director must decide how many fans should be used to circulate the air in the 25 sections of the warehouse. Due to limited budget, she decided to put a fan at the doors, refreshing two sections at the same time. Formulate a mathematical program to minimize the number of fans. Solve the problem on the map below using AMPL. How many fans she need and where should she put them?

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