当集合s中的元素都为自然数,且满足命题“如果x属于s,则8-x属于s”时,请问 1满足上述条件的集合s共有多

题目

当集合s中的元素都为自然数,且满足命题“如果x属于s,则8-x属于s”时,请问 1满足上述条件的集合s共有多
当集合s中的元素都为自然数，且满足命题“如果x属于s，则8-x属于s”时，请问 1满足上述条件的集合s共有多少个，请全部写出！
不懂一楼的回答

答案

{0,8}
{1,7}
{2,6}
{3,5}
{4}
{0,1,7,8}
{0,2,6,8}
{0,3,5,8}
{0,4,8}
{1,2,6,7}
{1,3,5,7}
{1,4,7}
{2,3,5,6}
{2,4,6}
{3,4,5}
{0,1,2,6,7,8}
{0,1,3,5,7,8}
{0,1,4,7,8}
{0,2,3,5,6,8}
{0,2,4,6,8}
{0,3,4,5,8}
{1,2,3,5,6,7}
{1,2,4,6,7}
{1,3,4,5,7}
{2,3,4,5,6}
{0,1,2,3,5,6,7,8}
{0,1,2,4,6,7,8}
{0,1,3,4,5,7,8}
{0,2,3,4,5,6,8}
{1,2,3,4,5,6,7}
{0,1,2,3,4,5,6,7,8}