KöMaL 2016 C1380
An odd number of digits are written on the circumference of a circle. Each of them is a 0, 1 or 2, and they are not all equal. In each step, we simultaneously write between every pair of adjacent numbers the remainder of their sum divided by 3, and then erase the original two numbers. Is it possible that all numbers become identical on the circumference of the circle after a few such steps?
Official text KöMaL. Quoted with source.
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