Word Game

Children play a word chain game. Each player must say a word that begins with the same character that the previous word ends with.

You are given a dictionary of words. Determine whether the children can play so that every word in the dictionary is used exactly once. All words in the dictionary are distinct. Words consist of the characters A to Z, a to z, and 0 to 9, and uppercase and lowercase letters are different characters.

The first line contains the number of words $N$ in the dictionary ($2 \le N \le 10\,000$). Each of the next $N$ lines contains one word. No word is longer than 10 characters.

If all words can be ordered according to the rules, print JAH on the first line, followed by exactly $N$ lines that give one possible order of the words, where each word begins with the same character that the previous word ended with. Otherwise, print EI on a single line.