Exercice 3

function lopt (p,e:real):real;
Begin
    l:=0;
    Repeat
        d:=(p-2*l)/Pi;
        s:=l*d;
        l:=s/d;
        p:=2*l+pi*d;
    Until (p<=e) or (l>p/2);
    lopt:=p;
end;