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 JAVA (judge verdict: Accepted)

import java.util.*;
import java.lang.*;
import java.io.*;

class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		String nl = System.getProperty("line.separator");
		StringBuilder p = new StringBuilder(1000);
		StringBuilder d = new StringBuilder(".");
		StringBuilder s = new StringBuilder("#");
		StringBuilder k = new StringBuilder(100);
		Scanner r = new Scanner(System.in);
		int h, w, i, ww;
		String u;
		for (i = 0; i < 4; ++i) {
			d.append(d);
			s.append(s);
		}
		ww = d.length();
		for ( ; (h = r.nextInt()) + (w = r.nextInt()) > 0; ) {
			for ( ; w > ww; ww += ww) {
				d.append(d);
				s.append(s);
			}
			p.append(u = s.substring(0,w)).append(nl);
			k.setLength(0);
			k.append(d.substring(0, w)).append(nl)
			.replace(0, 1, "#").replace(w - 1, w, "#");
			for (i = h - 2; i > 0; --i) {
				p.append(k);
			}
			p.append(u).append(nl).append(nl);
		}
		System.out.print(p);
	}
}