There are 1000 red balls and 1001 blue balls in a bag. You randomly take out 2 balls from the bag. If they happen to be of same colour, you replace them with red ball. If they are of different colour, you replace them with blue ball. The process is repeated till only one ball remains in the bag.
What is the colour of the last two remaining balls in the bag?

What is the colour of the last remaining ball in the bag?