program b_;
var f,g:text;
x1,y1,x2,y2,x3,y3,x4,y4,a,b,P:real;
begin
assign(f,'location.txt');
reset(f);
assign(g,'output.txt ');
rewrite(g);
Read(f,x1,y1,x2,y2,x3,y3,x4,y4);
if (abs((x2-x1)*(x4-x1)+(y2-y1)*(y4-y1))<1.0e-9) and
(x2-x1=x3-x4) and (y2-y1=y3-y4) then
begin
  a:=sqrt(sqr(x2-x1)+sqr(y2-y1));
  b:=sqrt(sqr(x3-x2)+sqr(y3-y2));
  P:=2*(a+b);
  write(g,P:5:3);
end
else write(g,'FALSE');  
Close(f);
Close(g);
end.