using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var array = new [] { 'b','c','d','f' };

        char[] alphabet = "abcdefghijklmnopqrstuvwxyz".ToCharArray();

        var startIndex = Array.IndexOf(alphabet, array.First());

        for (var i = startIndex; i < array.Length; i++) {

            if (array[i] != alphabet[i]) {

                Console.WriteLine(alphabet[i] + " " +  i);

                break;

            }

        }

    }

}