using System;
using System.Collections.Generic;
using System.Linq;

namespace P05.SnakeMoves
{
    class StartUp
    {
        static void Main(string[] args)
        {
            int[] dimensions = Console.ReadLine().Split(" ",StringSplitOptions.RemoveEmptyEntries).Select(int.Parse).ToArray();
            int rows = dimensions[0];
            int cols = dimensions[1];
            var matrix = new char[rows, cols];
            string input = Console.ReadLine();
            var snakeQueue = new Queue<char>(input);
            char oddSymbol = ' ';
            char evenSymbol = ' ';
            int counter = 0;
            for (int row = 0; row < rows; row++)
            {
                counter = 0;
                if (row % 2 == 1)
                {
                    oddSymbol = ' ';
                    if (snakeQueue.Any() && row > 0)
                    {
                        for (int col = cols - 1; col >= 0; col--)
                        {
                            oddSymbol = snakeQueue.Dequeue();
                            matrix[row, col] = oddSymbol;
                            counter++;
                            if (!snakeQueue.Any())
                            {
                                snakeQueue = new Queue<char>(input);
                                break;
                            }
                        }
                    }
                    for (int col = cols - 1 - counter; col >= 0; col--)
                    {
                        oddSymbol = snakeQueue.Dequeue();
                        matrix[row, col] = oddSymbol;
                    }
                }
                else
                {
                    evenSymbol = ' ';
                    if (snakeQueue.Any() && row > 0)
                    {
                        for (int col = 0; col < cols; col++)
                        {
                            evenSymbol = snakeQueue.Dequeue();
                            matrix[row, col] = evenSymbol;
                            counter++;
                            if (!snakeQueue.Any())
                            {
                                snakeQueue = new Queue<char>(input);
                                break;
                            }
                        }
                    }
                    for (int col = counter; col < cols; col++)
                    {
                        evenSymbol = snakeQueue.Dequeue();
                        matrix[row, col] = evenSymbol;
                    }
                }
            }
            PrintMatrix(rows, cols, matrix);
        }

        private static void PrintMatrix(int rows, int cols, char[,] matrix)
        {
            for (int row = 0; row < rows; row++)
            {
                for (int col = 0; col < cols; col++)
                {
                    Console.Write(matrix[row, col]);
                }
                Console.WriteLine();
            }
        }
    }
}