StrSymmetryPoint Submitted in: C#

public static int solution(string S)
        {
            var index = 0;
           if(string.IsNullOrEmpty(S) || S.Length%2 == 0)
            {
                index = -1;
            }
           else if(S.Length == 1)
            {
                index = 0;
            }
            else
            {
                var middle = S.Length / 2;
                bool isPadigram = true;
                for (int i = 0; i <= middle ; i++)
                {
                    if(S[i] != S[S.Length - 1 - i])
                    {
                        isPadigram = false;
                        break;
                    }
                }

                if (isPadigram)
                {
                    index = middle;
                }
                else
                {
                    index = -1;
                }
            }

            return index;
        }