n - 1 誰知趙家人的盤中餐 粒粒皆辛苦

https://www.youtube.com/watch?v=KoHeGxDuN9w

https://www.youtube.com/watch?v=oL51lGCSqrQ

if n = 1
1 - 1 = 0 
therefore, no one can take meals alone