>>13923193Every move has to be to the right or up to be the shortest track, so there are only ever one or two options from each point. The points below red points, the topmost points, and the rightmost points have 1 option and everything else has 2 options. At each step, you will move to the next \ diagonal. So we simply multiply the number of options at each diagonal by 2 and subtract the number of points with one option. So the answer will simply be
((((((((2*2-1)2*2-1)2*2-1)2*2-2)2-1)2-2)2-2)2-2) = 2698
