A group of students are taking Math, Psychology and History: 21 students are taking Math 18 students are taking Psychology 17 students are taking History 10 students are taking Math & Psychology 7...

A group of students are taking Math, Psychology and History:

21 students are taking Math

18 students are taking Psychology

17 students are taking History

10 students are taking Math & Psychology

7 students are taking Math & History

5 students are taking Psychology & History

2 students are taking all three classes

How many students are in the group?