01. Largest Common End

using System;
using System.Linq;

namespace _01._Largest_Common_End
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] firstArray = Console.ReadLine().Split(' ').ToArray();
            string[] secondArray = Console.ReadLine().Split(' ').ToArray();

            PrintTheLargestCommonEnd(firstArray, secondArray);
        }

        static void PrintTheLargestCommonEnd(string[] firstArray, string[] secondArray)
        {
            var counterLeftToRight = ScanTheArraysFromLeftToRight(firstArray, secondArray);
            var counterRightToLeft = ScanTheArraysFromRightToLeft(firstArray, secondArray);

            Console.WriteLine(counterLeftToRight + counterRightToLeft);

        }

        static int ScanTheArraysFromLeftToRight(string[] firstArray, string[] secondArray)
        {
            var counter = 0;

            for (int i = 0; i < Math.Min(firstArray.Length, secondArray.Length); i++)
            {
                if (firstArray[i] == secondArray[i])
                {
                    counter++;
                }

                else
                {
                    break;
                }
            }

            return counter;
        }

        static int ScanTheArraysFromRightToLeft(string[] firstArray, string[] secondArray)
        {
            var counter = 0;

            for (int i = Math.Max(firstArray.Length, secondArray.Length); i >= Math.Min(firstArray.Length, secondArray.Length) ; i--)
            {
                if (firstArray.Length > secondArray.Length)
                {
                    if (secondArray[i - Math.Abs(secondArray.Length - firstArray.Length) - 1] == firstArray[i - 1])
                    {
                        counter++;
                    }
                }
                else if (secondArray.Length > firstArray.Length)
                {
                    if (firstArray[i - Math.Abs(secondArray.Length - firstArray.Length) - 1] == secondArray[i - 1])
                    {
                        counter++;
                    }
                }
                else
                {
                    ScanTheArraysFromLeftToRight(firstArray, secondArray);
                }
            }

            return counter;
        }
    }
}