oh ok, 2.
you start at A. you take one carrier with you.
after the first day, you have eaten 1 of his 4 days of food, and he has eaten 1. he has 2 left.
after the second day he goes home, using 1 of his foods, he survives. you have gone forward and used 1 food of your own. 3 left.
after the 3rd day you have 2 left
after the 4th day you have 1 day left.
after the 5th day you have eaten, but run out of food.
while you are travelling on day 5, a carrier also travels from B (he eats 1 day of food getting to you, 3 left). you meet him at the end of your day.
day six you and the carrier travel to B and both eat, having 1 food left over
