=+4.13. Let o be a positive function of integers, and define B, as the set of x in (0, 1)

such that [x -p/2'\< 1/2'(2') holds for infinitely many pairs p, i. Adapting the proof of Theorem 1.6, show directly (without reference to Example 4.12)

that E;1/4(24) <œ implies À(B ) =0.