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 (1.42.0) (judge verdict: Accepted)

use std::collections::HashSet;
use whiteread::parse_line;

fn main() {
    let s: String = parse_line().unwrap();
    let s = s.as_str();
    let mut set = HashSet::new();
    for c in s.chars() {
        if !set.insert(c) {
            println!("no");
            return;
        }
    }
    println!("yes");
}