with(Math)for(t=atan2;[a,b,c,d,e,f,g,h]=readline().split(' ');)print(+(0>sin(p=t(b-f,a-e)-t(d-f,c-e))*sin(p-t(b-h,a-g)+t(d-h,c-g))))

Note that non-ascii characters in the above source code will be escaped (such as \x9f).

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