COVID19 health centers

Consider $1600$ buildings that are arranged as a $40 \times 40$ grid, Manhattan style. If it is required to select $\large n$ COVID19 health centers, such that in every $7 \times 7$ group of buildings you will have only one of the buildings to be used as a COVID19 health center to serve the other $48$ buildings.

What is the minimum number $\large n$ of buildings are you going to use as health centers from the $1600$ buildings?

If it is not possible to find an answer, give your answer as $0$ .

This is an original problem.