A grouped frequency distribution table with classes of equal sizes using $63-72$ $(72$ included$)$ as one of the class is constructed for the following data: $30, 32, 45, 54, 74, 78, 108, 112, 66, 76, 88,\ 40, 14, 20, 15, 35, 44, 66, 75, 84, 95, 96,\ 102, 110, 88, 74, 112, 14, 34, 44$ The number of classes in the distribution will be: