You are given a list of strings from the alien language's dictionary, where the strings in words are sorted lexicographically by the rules of this new language. Return a string of the unique letters in the new alien language sorted in lexicographically increasing order by the new language's rules. If there is no solution, return "". If there are multiple solutions, return any of them.
1 <= number of words <= 100 1 <= length of each word <= 100 word consists of only lowercase English letters
First line contains one integer N. Next line contains n Strings.
Return a string of the unique letters in the new alien language sorted in lexicographically increasing order.
5 wrt wrf er ett rftt