Physics Problem

16 adults, a 12-year-old, and a baby are traveling on a matatu (a 14-passenger minivan). This number does not include the driver and conductor. 5 people get off to allow 2 from the back seat to leave. The 5 return and rearrange themselves in the matatu, and are joined by 3 more, one with a 50 kilo bag of maize. The maize is hoisted to the roof of the matatu and secured with a single rope. At the next stop, the mother and baby leave, and 2 secondary school students with trunks and backpacks come aboard, as well as a woman holding 2 live chickens. The trunks are put in the small trunk space behind the rear seats. Two men leave at the next junction, replaced by a woman with a 3-year-old and 2 large shopping bags. She hands the 3-year old to the nearest passenger, and her bags to two other passengers. The matatu stops to pick up 2 additional passengers with suitcases. The suitcases join the sack of grain on the roof of the vehicle.  Two of the students leave and are replaced by a woman with a large basket of greens. 5 large boxes of grocery items are squeezed into spaces under the first two rows of seats for delivery to the next town, and 4 more go into overhead bins.

Question: Which are the most comfortable seats on the matatu?