Suppose the answer to the above question is a. A natural number that can be written as the sum of two composite numbers is called a "good number". Then how many "good numbers" are there among the natural numbers from 1 to a?
设上题答数是a．能写成两个合数之和的自然数称作"好数"．那么在1到a的自然数中"好数"共有多少个．
<gadget id="calculator">88 - 9</gadget>
<output>79</output>

<result>79</result>