Start

2018-05-12 00:00 UTC

CFT7

End

2018-05-13 00:00 UTC
The end is near!
Contest is over.
Not yet started.
Contest is starting in -315 days 20:19:33

Time elapsed

24:00:00

Time remaining

0:00:00

Problem J
No Duplicates

There is a game in which you try not to repeat a word while your opponent tries to see if you have repeated one.

"THE RAIN IN SPAIN" has no repeats.

"IN THE RAIN AND THE SNOW" repeats THE.

"THE RAIN IN SPAIN IN THE PLAIN" repeats THE and IN.

Write a program to test a phrase.

Input

Input is a line containing words separated by single spaces, where a word consists of one or more uppercase letters. A line contains no more than $80$ characters.

Output

The output is "yes" if no word is repeated, and "no" if one or more words repeat.

Sample Input 1 Sample Output 1
THE RAIN IN SPAIN
yes
Sample Input 2 Sample Output 2
IN THE RAIN AND THE SNOW
no
Sample Input 3 Sample Output 3
THE RAIN IN SPAIN IN THE PLAIN
no