using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("OneEditApart: " + OneEditApart("cat", "dog"));

        Console.WriteLine("OneEditApart: " + OneEditApart("cat", "cats"));

        Console.WriteLine("OneEditApart: " + OneEditApart("cat", "cut"));

        Console.WriteLine("OneEditApart: " + OneEditApart("cat", "cast"));

        Console.WriteLine("OneEditApart: " + OneEditApart("cat", "at"));

        Console.WriteLine("OneEditApart: " + OneEditApart("cat", "act"));

    }

    public static bool OneEditApart(string s, string t)

    {

        for (int i = 0; i < Math.Min(s.Length, t.Length); i++)

        {

            if (s[i] != t[i])

            {

                if (s.Length == t.Length)

                {

                    return s.Substring(i + 1).Equals(t.Substring(i + 1)); //if the same size we delete from both, the character needs to get replaced if equal

                }

                else if (s.Length < t.Length)

                {

                    return s.Substring(i).Equals(t.Substring((i + 1))); //if t is longer we delete from t

                }

                else

                {

                    return t.Substring(i).Equals(s.Substring(i + 1)); //if s is longer we delete from s

                }

            }

        }

        return Math.Abs(s.Length - t.Length) == 1; //if we are here then all the characters were the same, then we should delete the end of the longer string

    }

}