One cannot be called a prime number, since a prime has 2 divisors, and one is 1. The number 1 is not classified as either simple or composite
Here 1 is considered a prime number

please explain the condition of the task
If it is clear where the winning numbers come from, then why in the 2nd example, with n = 4, Paul won

there is an error with examples here. Try to do it with your hands with 810,812 and 818. Here they say that 833 will be done in one iteration. Before work, we will receive 64 + 9 + 9 = 82. In the first iteration there will be 68. 68 != 82 And what is the fun of such examples?