Grave City is considering the relocation of several police substations to obtain better enforcement in high-crime areas. The locations under consideration together with the areas that can be covered from these locations are given in the following table: Locations Areas 1.4,7 1,3.5.7 1,2,5 2.5.6 3,4.7 4.6 Areas 2 and 6 must be covered by at least 2 locations. The rest of the areas must be covered by at least 1 location. What is the minimum number of locations