The awkward bag
You have 17 blue balls and 17 red balls in a bag. You want to free yourself of them, but you have one condition. You have to take out 2 ball at once. If you take balls with different colors, you will put another red ball. If you take balls with same color, you will put another blue ball. What will be the color of the last ball in the bag?
Important: No matter what, each time you take out 2 balls, you have to put another one(the correct one). Even if you someway get 2 balls left, and you take out these 2 balls, you have to put another ball.