On still water, Olive can paddle her kayak $5\mathrm{m}/\mathrm{s}$. She wishes to cross a river which flows east at $2\mathrm{m}/\mathrm{s}$. If Olive is standing on the south bank, and would like to reach a point directly across the river on the north bank, at what angle upstream (west of north) should she point her Kayak?