Algo(T,X,k1,k2)
If T != NIL
    If T->Key < k2
        sx = Algo(T->sx,x,k1,k2)
        dx= Algo(T->dx,x,k1,k2)
        tot = sx+dx
        if tot <=x && T->key > k1
        T=Cancella(T)
        tot=tot+1
        return tot
else
return 0