(1+i)^2 = 2i
(1+i)^4 = (2i)^2 = -4
(1+i)^8 = (-4)^4 = 16
(1+i)^17 = 16^2 * (1+i) = 256*(1+i)
(1-i)^2 = -2i
(1-i)^4 = (-2i)^2 = -4
(1-i)^8 = (-4)^4 = 16
(1-i)^17 = 16^2 * (1-i) = 256*(1-i)
S = (1+i)^17 - (1-i)^17 = 256*(1+i) - 256*(1-i) = 512*i
|S| = |512*i| = 512