using System;

using System.Linq;

public class Program

{

    static char GetFirst(string input)

    {

        var arr = input.AsEnumerable().ToArray();

        int strLen = input.Length;

        char first = '-';

        for(int i = 0; i < strLen; i++)

        {

            bool found = false;

            for(int j = 0; j < strLen; j++)

            {

                if(arr[i] == arr[j])

                {

                    if(i != j)

                    {

                        found = true;

                        break;

                    }

                }

            }

            if(!found)

            {

                first = arr[i];

                break;

            }

        }

        return first;

    }

    public static void Main()

    {

        Console.WriteLine("Hello World");

        char ch = GetFirst("aabdced");

        Console.Write(ch);

    }

}