Largest_Common_End

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Largest_Common_End
{
    class Largest_Common_End
    {
        static void Main(string[] args)
        {
            string[] firstArray = Console.ReadLine().Split(' ').ToArray();
            string[] secondArray = Console.ReadLine().Split(' ').ToArray();
            int output = LargestCommonEnd(firstArray, secondArray);
            Console.WriteLine(output);
        }

        static int LargestCommonEnd(string[] firstArray, string[] secondArray)
        {
            var leftCount = 0;
            var rightCount = 0;
            while ((leftCount < firstArray.Length && leftCount < secondArray.Length) &&
                   (rightCount < firstArray.Length && rightCount < secondArray.Length))
            {
                if (firstArray[leftCount] == secondArray[leftCount]) leftCount++;
                else if (firstArray[firstArray.Length - rightCount - 1] == secondArray[secondArray.Length - rightCount - 1]) rightCount++;
                else break;
            }

            if (leftCount < rightCount) return rightCount;
            else return leftCount;
        }
    }
}