program Project1;

{$APPTYPE CONSOLE}

var
x1,x2,x3,y1,y2,y3:INTEGER;
a,b,c,s,p:real;begin
readln(x1,y1,x2,y2,x3,y3);
a:=sqrt(sqr(x2-x1)+sqr(y2-y1));
b:=sqrt(sqr(x3-x2)+sqr(y3-y2));
c:=sqrt(sqr(x3-x1)+sqr(y3-y1));
p:=(a+b+c)/2;
if (p<a) or (p<b) or (p<c) then writeln('trukyk ne isnye')
else
begin
s:=sqrt(p*(p-a)*(p-b)*(p-c));
writeln(s);
end;
readln(s);
END.