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 Rust (1.15.1) (judge verdict: Wrong Answer)

use std::collections::HashSet;
fn main() {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    let mut h: HashSet<char> = HashSet::new();
    for c in &s.trim().chars().collect::<Vec<char>>() {h.insert(*c);}
    println!("{}", if h.len() == s.len() {"yes"} else {"no"});
}