You are given n words. Can you permute the words (not their letters) so that the second word begins with the last letter of the first word, the third word begins with the last letter of the second word, and so on?
Input
Input consists of several cases, each with n, followed by n words made up of between 1 and 10 lowercase letters. You can assume 1 ≤ n ≤ 105.
Output
For every case, print “yes” if it is possible arrange all the words like in the game of domino. Otherwise, print “no”.
Input
3 the easiest task 2 or not 1 hello 2 ab abc 5 za z zz zz bz 3 a a a
Output
yes no yes no yes yes