var x1,y1,x2,y2,x3,y3,x4,y4:integer;
s1,s2,s3,s:real;
begin
assign(input,'task7.in');
reset(input);
assign(output,'task7.out');
rewrite(output);
readln(x1,y1,x2,y2,x3,y3,x4,y4);
s:=1/2*abs(x1*y2-x2*y1+x2*y3-x3*y2+x3*y1-x1*y3);
s1:=1/2*abs(x1*y2-x2*y1+x2*y4-x4*y2+x4*y1-x1*y4);
s2:=1/2*abs(x1*y4-x4*y1+x4*y3-x3*y4+x3*y1-x1*y3);
s3:=1/2*abs(x4*y2-x2*y4+x2*y3-x3*y2+x3*y4-x4*y3);
if (s=s1+s2+s3) then writeln('Yes') else writeln('No');
close(input);
close(output);
end.