Each of the numbers in the set
![N = \{1, 2, 3, \cdots, n - 1\}](/media/m/3/e/1/3e11e726ed5343deeab2a534d844bb43.png)
, where
![n \geq 3](/media/m/5/4/8/54807b3bf99aa939833fe57bf8d891d3.png)
, is colored with one of two colors, say red or black, so that:
(i)
![i](/media/m/3/2/d/32d270270062c6863fe475c6a99da9fc.png)
and
![n - i](/media/m/e/7/9/e79472afe57a20b8bb05e487a6068efa.png)
always receive the same color, and
(ii) for some
![j \in N](/media/m/f/6/d/f6dc0f86b50aaaed29ebf91ed57548ba.png)
, relatively prime to
![n](/media/m/a/e/5/ae594d7d1e46f4b979494cf8a815232b.png)
,
![i](/media/m/3/2/d/32d270270062c6863fe475c6a99da9fc.png)
and
![|j - i|](/media/m/b/e/a/bea5be721428f50e9830f3006a6fba49.png)
receive the same color for all
![i \in N, i \neq j.](/media/m/4/a/2/4a249bf9bd3c03b860b536cb7906639a.png)
Prove that all numbers in
![N](/media/m/f/1/9/f19700f291b1f2255b011c11d686a4cd.png)
must receive the same color.
%V0
Each of the numbers in the set $N = \{1, 2, 3, \cdots, n - 1\}$, where $n \geq 3$, is colored with one of two colors, say red or black, so that:
(i) $i$ and $n - i$ always receive the same color, and
(ii) for some $j \in N$, relatively prime to $n$, $i$ and $|j - i|$ receive the same color for all $i \in N, i \neq j.$
Prove that all numbers in $N$ must receive the same color.