1.There are 32 students in a group, and each of them attends a special course in philosophy or in psychology or in history. 21 students attend course in philosophy, 17 - in psychology. 13 students attend courses in philosophy and psychology, 8 - in philosophy and history, 5 - in psychology and history. 3 students attend all the three special courses. How many students do attend course in history? How many students do attend exactly 2 courses? Exactly 1 course?

2.Solve second order recurrence equation