There are 18 students in a room. How many students are not majoring in math or science or computer science ?

7 of them are math majors

10 of them are science majors

10 of them are computer science majors

4 of them are math and cs majors

3 of them are science and math majors

5 of them are cs and science majors

1 of them is a math, cs and science major