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

namespace MatrixShuffle
{
    class Program
    {
        static void Main(string[] args)
        {
            int matrixSize = int.Parse(Console.ReadLine());
            string input = Console.ReadLine();
            char[,] matrix = new char[matrixSize, matrixSize];
            int row = 0;
            int col = 0;
            string direction = "right";
            int matrixLength = matrixSize * matrixSize;


                for (int i = 0; i < matrixLength; i++)
                {
                    if (direction == "right" && (col > matrixSize - 1 || matrix[row, col] != default(char)))
                    {
                        direction = "down";
                        col--;
                        row++;
                    }
                    if (direction == "down" && (row > matrixSize - 1 || matrix[row, col] != default(char)))
                    {
                        direction = "left";
                        row--;
                        col--;
                    }
                    if (direction == "left" && (col < 0 || matrix[row, col] != default(char)))
                    {
                        direction = "up";
                        col++;
                        row--;
                    }

                    if (direction == "up" && (row < 0 || matrix[row, col] != default(char)))
                    {
                        direction = "right";
                        row++;
                        col++;
                    }
                    if (i > input.Length - 1)
                    {
                        matrix[row, col] = ' ';
                    }
                    else
                    {
                        matrix[row, col] = input[i];
                    }

                    if (direction == "right")
                    {
                        col++;
                    }
                    if (direction == "down")
                    {
                        row++;
                    }
                    if (direction == "left")
                    {
                        col--;
                    }
                    if (direction == "up")
                    {
                        row--;
                    }
                }

                List<char> firstString = new List<char>();
                List<char> secondString = new List<char>();

                for (int rr = 0; rr < matrix.GetLength(0); rr++)
                {
                    if (rr % 2 == 0)
                    {
                        for (int cc = 0; cc < matrix.GetLength(1); cc = cc + 2)
                        {
                            firstString.Add(matrix[rr, cc]);
                        }
                        for (int cc = 1; cc < matrix.GetLength(1); cc = cc + 2)
                        {
                            secondString.Add(matrix[rr, cc]);
                        }
                    }
                    else
                    {
                        for (int cc = 0; cc < matrix.GetLength(1); cc = cc + 2)
                        {
                            secondString.Add(matrix[rr, cc]);
                        }
                        for (int cc = 1; cc < matrix.GetLength(1); cc = cc + 2)
                        {
                            firstString.Add(matrix[rr, cc]);
                        }
                    }
                }

                bool isPalindrome = false;

                string convertFirstString = new string(firstString.ToArray());
                string convertSecondString = new string(secondString.ToArray());

                string straightInput = convertFirstString + convertSecondString;
                string straightInputToLower = straightInput.ToLower();
                //var a = straightInputToLower.ToCharArray();
                //Array.Reverse(a);

                var original = straightInputToLower;
                var reversed = new string(original.ToCharArray().Reverse().ToArray());

                if (original == reversed)
                {
                    isPalindrome = true;
                }

                if (isPalindrome)
                {
                    Console.WriteLine("<div style='background-color:#4FE000'>" + straightInput + "</div>");
                }
                else
                {
                    Console.WriteLine("<div style='background-color:#E0000F'>" + straightInput + "</div>");
                }
        }
    }
}