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 Kotlin (1.0.0) (judge verdict: Accepted)

import java.io.PrintWriter
val pw = PrintWriter(System.out)

fun main(args : Array<String>) {
    func()
    pw.flush()
}

fun func() {
    val s = next()
    val ss = mutableMapOf<Char, Char>()

    for (i in 0 until s.length) {
        if (ss[s[i]] == null) {
            ss[s[i]] = s[i]
        } else {
            println("no")
            return
        }
    }

    println("yes")
}

fun next() = readLine()!!

fun println(value : Any) {
    pw.println(value)
}