Problem:
Score : 200 points

Problem Statement

You are given a string S consisting of lowercase English letters. Determine whether all the characters in S are different.

Constraints

2 ≤ |S| ≤ 26, where |S| denotes the length of S.

S consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

S

Output

If all the characters in S are different, print yes (case-sensitive); otherwise, print no.

Sample Input 1

uncopyrightable

Sample Output 1

yes

Sample Input 2

different

Sample Output 2

no

Sample Input 3

no

Sample Output 3

yes

Solution in Scala (2.13.1) (judge verdict: Accepted)

object Main extends App{
  import scala.io.StdIn.readLine
  
  val s = readLine.split("").toList
  val delvaried = s.foldLeft(List(""))((a,b) => if(a.contains(b)){a}else a :+ b)
  
  if(s.length + 1 == delvaried.length)println("yes");
  else println("no")

}