solve it as integer programming solve it by excel solver

The treasure of King Tut are one display in a museum. The layout of the museum is shown below with the different room joined by open doors. A guard standing at a door can watch two adjoining rooms. The museum wants to ensure guard present in every room, using the minimum number possible. Room 1 Room 2 Exit Room Room Room Entrance 5 4 3 IRO Room 6 Room 7 Room 8 - 1- Formulate the problem. 2- What is the optimum solution using Excel solver