0000 1 Yes 1
000 10 is 2.
000 1 1 is 3.
The number of numbers represents
1 1 1 1 1
16,8,4,2, 1。
So xoxxo is 0 100 1 of 9.
The maximum number that can be expressed is16+8+4+2+1= 31.
28 is 16+8+4, which means:1100, that is, oooxx.