ison(C, P) = True
ison(C, Q) = True
P = (398011447251267732058427934569710020713094, 548950454294712661054528329798266699762662)
Q = (139255151342889674616838168412769112246165, 649791718379009629228240558980851356197207)
s * P = (730393937659426993430595540476247076383331, 461597565155009635099537158476419433012710)
t * Q = (500532897653416664117493978883484252869079, 620853965501593867437705135137758828401933)