var
x1, x2, x3, y1, y2, y3, p: real;

function len(x1, y1, x2, y2: real): real;
begin
len := sqrt(sqr(x2 - x1) + sqr(y2 - y1));
end;

begin
readln(x1, y1, x2, y2, x3, y3);
p := len(x1, y1, x2, y2) + len(x1, y1, x3, y3) + len(x2, y2, x3, y3);
writeln(p:8:3);
end.