In a class of 35 students, 10 speak Ilocano, 18 speak Bicolano, 16 speak Cebuano, 5 speaks both Bicolano and Ilocano, 2 speaks both Ilocano and Cebuano, 9 speaks both bicolano and cebuano, and 2 speaks all three languages.  How many students do not speak any of the 3 languages?