Suppose that the numbers 0,.,9 are pushed onto a stack in that order, but pops occur at random points between various pushes (multiple pops can occur in a row and every item is popped in the end). The following is a valid sequence in which the values in the stack could have been popped: 3, 2, 6, 5,7, 4, 1, 0, 9, 8 Explain clearly why 3, 2, 6, 4,7, 5, 1,0,9, 8 is not a valid sequence in which the values could have been popped off the stack