Var a1,b1,a2,b2,a3,b3:integer;
p,a,b,c:real;
procedure dlina (x1,x2,y1,y2:integer; var d:real);
begin
d:=sqrt(sqr(x2-x1)+sqr(y2-y1));
end;
begin
read(a1,b1,a2,b2,a3,b3);
dlina(a1,a2,b1,b2,a);
dlina(a2,a3,b2,b3,b);
dlina(a3,a1,b3,b1,c);
p:=a+b+c;
write(p:0:2);
end.