long stringLength = Convert.ToInt32(Console.ReadLine());
            string S = Console.ReadLine();
            string T = Console.ReadLine();
            long temp = 0;
            bool check = false;
            for (long i = 0; i < stringLength; i++)
            {
                S = S[Convert.ToInt32(stringLength) - 1] +
                                     S.Substring(0,  Convert.ToInt32(stringLength) - 1);
                if (S == T)
                {
                    temp = i + 1;
                    check = true;
                    break;
                }
            }
            if (check && temp < stringLength)
                Console.WriteLine(temp);
            else
                Console.WriteLine(-1);