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 C# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.IO;

class Solve
{
    static void Main(string[] args) {
        var S = Console.ReadLine();
        var set = new HashSet<char>();
        var answer = string.Empty;
        foreach (var let in S) {
            if (set.Contains(let)) {
                answer = "no";
                break;
            }
            set.Add(let);
        }
        if (set.Count == S.Length) answer = "yes";
        var writer = new StreamWriter(Console.OpenStandardOutput()) {AutoFlush = false};
        Console.SetOut(writer);
        Console.WriteLine(answer);
        Console.Out.Flush();
    }
}