Odd String

You are given a string $S$ of length $N$ consisting only of lowercase English letters. A string is called an **odd string** if and only if: - For every pair of indices $i < j$ such that $S_i = S_j$, the distance between them is odd, i.e. $ (j - i) $ **is odd**. - In other words, no two equal characters are allowed to appear at an even distance from each other. You are allowed to rearrange the c