program pr3;
var x1,y1,x2,y2,x3,y3:real;
a,b,c,p:real;
procedure lin(x1,y1,x2,y2:real; var l:real);
begin
l:=sqrt(sqr(x2-x1)+sqr(y2-y1));
end;
begin
read(x1,y1,x2,y2,x3,y3);
lin(x1,y1,x2,y2,a);
lin(x2,y2,x3,y3,b);
lin(x3,y3,x1,y1,c);
p:=a+b+c;
writeln(p);
end.