A two-period consumer maximises $U(C_1, C_2) = \log C_1 + \tfrac{1}{1+\rho}\log C_2, \qquad \rho > 0,$ subject to $C_1 + S = w$ and $C_2 = (1+r) S$, with $w, r > 0$. If $w$ rises by $1\%$ and $r$ falls by $1\%$, then $S$