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 provides
//
// File:  b.go
// Author: ymiyamoto
//
// Created on Thu Jan 17 11:41:22 2019
//
package main

import "fmt"

func main() {
	var S string
	fmt.Scan(&S)

	for i := range S {
		for j := i + 1; j < len(S); j++ {
			if S[i] == S[j] {
				fmt.Println("no")
				return
			}
		}
	}
	fmt.Println("yes")
}