bao nhiêu số khác 9 đây
999999999999299999999999999999999999999999
999999999999999999969999939999999999999999
999999999999999999999999939999999992999999
999999999999999999999999199999999999999999
999999999999999969999999999999999999999999
999999999499999999999999979999999999999999
999999999999999999999999999939999999999999