Помогите срочно пжCh3-Ch-Ch3-Ch-Ch3-Ch2-Ch-Ch3-Ch3

1)-ch-ch-ch*3-ch*2-ch-ch*3-ch
2)-ch-ch-3ch-ch*2-ch-ch*3-ch
3)-ch-ch-3ch-2ch-ch-ch*3-ch
4)-ch-ch-3ch-2ch-ch-3ch-ch
= -12ch