Among a group of 165 students 8 are taking calculus

Among a group of 165 students 8 are taking calculus, discrete structures, and computer science; 33 are taking calculus and computer science; 20 are taking calculus and discrete structures; 24 are taking discrete structures and computer science; 79 are taking calculus; 83 are taking discrete structures; and 63 are taking computer science. How many are taking none of the three subjects? Show work please