using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(traverse(new [] {1, 2, 3, 4, 5, 10, 15, 20, 25, 24, 23, 22, 21, 16, 11, 6, 7, 8, 9, 14, 19, 18, 17, 12, 13}, 5, 5));

    }

    static int getIndex(int x, int y, int colums)

    {

      return y + x * colums;

    }

​

    static String traverse(int[] matrix, int rows, int columns)

    {

      int rowStart=0;

      int rowLength = rows-1;

      int colStart=0;

      int colLength = columns-1;

​

      String output = "";

      while(rowStart <= rowLength && colStart <= colLength)

      {

        for (int i = rowStart; i <= colLength; i++)

        {

          output += matrix[getIndex(rowStart, i, columns)] + ", ";

        }

​

        for (int j = rowStart+1; j <= rowLength; j++)

        {

          output += matrix[getIndex(j, colLength, columns)] + ", ";

        }

​

        if(rowStart+1 <= rowLength)

        {

          for (int k = colLength-1; k >= colStart; k--)

          {

            output += matrix[getIndex(rowLength, k, columns)] + ", ";

          }

        }

​

        if(colStart+1 <= colLength)

        {

          for (int k = rowLength-1; k > rowStart; k--)

          {

            output += matrix[getIndex(k, colStart, columns)] + ", ";

          }

        }

​

        rowStart++;

        rowLength--;

        colStart++;

        colLength--;

      }

​

      return output.Substring(0, output.Length - 2);

    }

​

​

​

}