public static void Main()
Console.WriteLine("Enter a string: ");
Sentence=Console.ReadLine();
Sentence=Sentence.ToLower();
Sentence=Sentence.Replace(" ","");
Sentence=Sentence.Trim();
for(int sen=0; sen<Sentence.Length;sen--)
Console.WriteLine(Sentence);
string sub=Sentence.Substring(0,1);
others=Sentence.IndexOf(sub);
others=Sentence.IndexOf(sub,others +1);
Console.WriteLine("{0} - {1}",sub,counter);
Sentence=Sentence.Replace(sub,"");