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: Accepted)

    #![allow(unused_imports)]
    #![allow(dead_code)]
    use std::io::prelude::*;
    use std::cmp::{max, min};
    use std::collections::{BinaryHeap, VecDeque};

    const MOD: i64 = 1e9 as i64 + 7; 

    fn main(){
        let s: Vec<char> = read::<String>().chars().collect();
        let mut e = [false; 26];
        let mut f = true;
        for i in s{
            let x = (i as u8 - b'a') as usize;
            if e[x]{
                f = false;
                break;
            }
            e[x] = true;
        }
        let ans = if f {"yes"} else {"no"};
        println!("{}", ans);
    }

    fn read<T>() -> T
    where
        T: std::str::FromStr,
    {
        let stdin = std::io::stdin();
        let token: String = stdin
            .lock()
            .bytes()
            .map(|c| c.unwrap() as char)
            .skip_while(|c| c.is_whitespace())
            .take_while(|c| !c.is_whitespace())
            .collect();
        token.parse().ok().unwrap()
    }