using System;

public class Program

{

    public static void Main()

    {

        string input = "abca";

        Console.WriteLine("Hello World");

        bool hasUniqueChars = new Program().strHasUniqueChars(input);

        if (hasUniqueChars)

        {

            Console.WriteLine(string.Format("'{0}' has all unique characters", input));

        }

        else

        {

            Console.WriteLine(string.Format("'{0}' does not have all unique characters", input));

        }

    }

    public bool strHasUniqueChars(string input)

    {

        for (int i=0; i<input.Length; i++)

        {

            int first = input.IndexOf(input[i]);

            int last = input.LastIndexOf(input[i]);

            if (first != last)

            {

                return false;

            }

        }

        return true;

    }

}