In a biochemical oxygen demand (BOD) test, 15 ml of wastewater sample was diluted with distilled water to completely fill a 300 ml BOD bottle and incubated at 20 \(^{\circ}\text{C}\) for 5 days. The dissolved oxygen (DO) level before and after incubation are 9.2 mg liter\(^{-1}\) and 4.4 mg liter\(^{-1}\), respectively. The BOD of the sample, in mg liter\(^{-1}\), is . (answer in integer)