Problem:
Print a Frame

Draw a frame which has a height of H cm and a width of W cm. For example, the following figure shows a frame which has a height of 6 cm and a width of 10 cm.

##########
#........#
#........#
#........#
#........#
##########

Input

The input consists of multiple datasets. Each dataset consists of two integers H and W separated by a single space.

The input ends with two 0 (when both H and W are zero).

Output

For each dataset, print the frame made of '#' and '.'.

Print a blank line after each dataset.

Constraints

3 ≤ H ≤ 300

3 ≤ W ≤ 300

Sample Input

3 4
5 6
3 3
0 0

Sample Output

####
#..#
####

######
#....#
#....#
#....#
######

###
#.#
###

Solution in C# (judge verdict: Accepted)

using System;
using System.Linq;

namespace C_sharp
{
    class Program
    {
        static void Main(string[] args)
        {
            while (true)
            {
                var items = Console.ReadLine().Split();
                
                var H = int.Parse(items[0]);
                var W = int.Parse(items[1]);

                if (H == 0 && W == 0)
                {
                    break;
                }

                var edge = new string('#', W);
                edge += "\n";

                var inner = new string('.', W - 2);
                var inner_line = "#" + inner + "#\n";
                var inner_rect = string.Concat(Enumerable.Repeat(inner_line, H - 2));

                var frame = edge + inner_rect + edge;

                Console.WriteLine(frame);
            }
        }
    }
}