Alice chooses a prime number p>2 and then Bob chooses a positive integer n0. Alice, in the first move, chooses an integer n1>n0 and calculates the expression s1=n0n1+n1n0; then Bob, in the second move, chooses an integer n2>n1 and calculates the expression s2=n1n2+n2n1; etc. one by one. (Each player knows the numbers chosen by the other in the previous moves.) The winner is the one who first chooses the number nk such that p divides sk(s1+2s2+⋅⋅⋅+ksk). Who has a winning strategy?Proposed by Borche Joshevski, Macedonia JuniorBalkanshortlist2021number theorygameexponential