Solve exercise 1
Solve exercise 2
Solve exercise 3
Solve exercise 4
Improve exercise 4 solution
Solve exercise 5
Solve exercise 6
Solve exercise 7
Solve exercise 8
Solve exercise 9
Solve exercise 10
Solve exercise 11
Solve exercise 12
Solve exercise 13
Solve exercise 14
Solve exercise 15
Solve exercise 16
Solve exercise 17
Solve exercise 18
Solve exercise 19