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)

fn main()
{
    let mut buf = String::new();
    std::io::stdin().read_line(&mut buf).unwrap();
    buf.trim();
    
    let mut ans = true;
    for (i,c1) in buf.chars().enumerate() {
        for (j,c2) in buf.chars().enumerate() {
            if i!=15 && j!=15 && i!=j && c1==c2 { ans = false; }
        }
    }
    
    if ans {
        println!("yes");
    } else {
        println!("no");
    }
}