In a pot, there are 75 white beans and 150 black beans. By the pot, there's a bag of black beans. A playful chef takes out the beans from the pot one by one like this: he randomly picks two beans- if at least one is black, he puts it in the black beans bag and the other one (regardless of its colour) back into the pot. If both beans he picked are white, he throws them away and puts a black bean from the bag into the pot.
Each time he does that, the pot holds fewer beans, and in the end only one bean is left in the pot. What is its colour?