Suppose that we push integers 0 through 9 in order onto an empty stack. However, a number of topop operations are performed randomly in-between pushes, where topop prints and removes the top item in the stack (top+pop). Which of the following sequences cannot occur? Justify your answer clearly. (3 marks) i) 4321098765 ii) 4321056789 iii) 4376852910 iv) 4687532901