Question 4. In a classroom of 33 students, 19 students are wearing glasses, 13 are wearing sweaters, 9 are wearing hats, 3 are wearing glasses and sweaters, 5 are wearing a sweater and a hat, 4 are wearing glasses and a hat, and 2 are wearing glasses, a sweater, and a hat. How many students are NOT wearing ANY of the three items (glasses, a sweater, or a hat)?.