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"
)
  func main(){
    var s string
    var i, j int
    fmt.Scan(&s)
    for i=0;i<len(s)-1;i++{
      for j=i+1;j<len(s);j++{
        if s[i]==s[j]{
          fmt.Println("no")
          return 
        }
      }
    }
   fmt.Println("yes")
 }