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 Go (1.6) (judge verdict: Accepted)

package main

import (
	"fmt"
	"log"
)

func main() {
	log.SetFlags(log.Lshortfile)
	var S string
	fmt.Scan(&S)
	ans := "yes"
	for i := 0; i < len(S); i++ {
		for j := i + 1; j < len(S); j++ {
			if S[i] == S[j] {
				ans = "no"
			}
		}
	}
	fmt.Println(ans)
}