Problem 3. During the physical education class, the entire class lined up by height (all children have different heights). Dima noticed that the number of people taller than him is four times the number of people shorter than him. And Lёnya noticed that the number of people taller than him is three times less than the number of people shorter than him. How many people are there in the class, if it is known that there are no more than 30 people?