

import java.util.*;

public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		// sb.append("");// ??????????????\???????????????
		int h, w, c;
		c = 0;// ?????¶??§???????????°

		while (true) {
			h = scan.nextInt();// ????????????
			w = scan.nextInt();// ?¨??????????
			// h??¨w?????¨??????0????????£?????¨??????????????????????????????
			if ((h == 0) & (w == 0)) {
				break;
			}
			//????????????????????????
			for(int count = 0;count<h;count++){
				//?¨??????????????????????
				for(int count2 = 0;count2<w;count2++){
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				}
				sb.append("\n");
				c = count+1;
					
			}

			System.out.println(new String(sb));
			// StringBuilder????????????????????????
			sb.delete(0, sb.length());
			c = 0;// ?????¶??§???????????°????????????
		}

	}
} import java.util.*; util.* java public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		// sb.append("");// ??????????????\???????????????
		int h, w, c;
		c = 0;// ?????¶??§???????????°

		while (true) {
			h = scan.nextInt();// ????????????
			w = scan.nextInt();// ?¨??????????
			// h??¨w?????¨??????0????????£?????¨??????????????????????????????
			if ((h == 0) & (w == 0)) {
				break;
			}
			//????????????????????????
			for(int count = 0;count<h;count++){
				//?¨??????????????????????
				for(int count2 = 0;count2<w;count2++){
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				}
				sb.append("\n");
				c = count+1;
					
			}

			System.out.println(new String(sb));
			// StringBuilder????????????????????????
			sb.delete(0, sb.length());
			c = 0;// ?????¶??§???????????°????????????
		}

	}
} Main public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		// sb.append("");// ??????????????\???????????????
		int h, w, c;
		c = 0;// ?????¶??§???????????°

		while (true) {
			h = scan.nextInt();// ????????????
			w = scan.nextInt();// ?¨??????????
			// h??¨w?????¨??????0????????£?????¨??????????????????????????????
			if ((h == 0) & (w == 0)) {
				break;
			}
			//????????????????????????
			for(int count = 0;count<h;count++){
				//?¨??????????????????????
				for(int count2 = 0;count2<w;count2++){
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				}
				sb.append("\n");
				c = count+1;
					
			}

			System.out.println(new String(sb));
			// StringBuilder????????????????????????
			sb.delete(0, sb.length());
			c = 0;// ?????¶??§???????????°????????????
		}

	} main {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		// sb.append("");// ??????????????\???????????????
		int h, w, c;
		c = 0;// ?????¶??§???????????°

		while (true) {
			h = scan.nextInt();// ????????????
			w = scan.nextInt();// ?¨??????????
			// h??¨w?????¨??????0????????£?????¨??????????????????????????????
			if ((h == 0) & (w == 0)) {
				break;
			}
			//????????????????????????
			for(int count = 0;count<h;count++){
				//?¨??????????????????????
				for(int count2 = 0;count2<w;count2++){
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				}
				sb.append("\n");
				c = count+1;
					
			}

			System.out.println(new String(sb));
			// StringBuilder????????????????????????
			sb.delete(0, sb.length());
			c = 0;// ?????¶??§???????????°????????????
		}

	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) StringBuilder sb = new StringBuilder(); sb new StringBuilder() int h h w w c; c c = 0 c 0 while (true) {
			h = scan.nextInt();// ????????????
			w = scan.nextInt();// ?¨??????????
			// h??¨w?????¨??????0????????£?????¨??????????????????????????????
			if ((h == 0) & (w == 0)) {
				break;
			}
			//????????????????????????
			for(int count = 0;count<h;count++){
				//?¨??????????????????????
				for(int count2 = 0;count2<w;count2++){
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				}
				sb.append("\n");
				c = count+1;
					
			}

			System.out.println(new String(sb));
			// StringBuilder????????????????????????
			sb.delete(0, sb.length());
			c = 0;// ?????¶??§???????????°????????????
		} true {
			h = scan.nextInt();// ????????????
			w = scan.nextInt();// ?¨??????????
			// h??¨w?????¨??????0????????£?????¨??????????????????????????????
			if ((h == 0) & (w == 0)) {
				break;
			}
			//????????????????????????
			for(int count = 0;count<h;count++){
				//?¨??????????????????????
				for(int count2 = 0;count2<w;count2++){
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				}
				sb.append("\n");
				c = count+1;
					
			}

			System.out.println(new String(sb));
			// StringBuilder????????????????????????
			sb.delete(0, sb.length());
			c = 0;// ?????¶??§???????????°????????????
		} h = scan.nextInt() h scan.nextInt() scan.nextInt scan w = scan.nextInt() w scan.nextInt() scan.nextInt scan if ((h == 0) & (w == 0)) {
				break;
			} (h == 0) & (w == 0) (h == 0) h 0 (w == 0) w 0 {
				break;
			} break; for(int count = 0;count<h;count++){
				//?¨??????????????????????
				for(int count2 = 0;count2<w;count2++){
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				}
				sb.append("\n");
				c = count+1;
					
			} int count = 0; int count = 0; count 0 count<h count h count++ count++ count {
				//?¨??????????????????????
				for(int count2 = 0;count2<w;count2++){
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				}
				sb.append("\n");
				c = count+1;
					
			} {
				//?¨??????????????????????
				for(int count2 = 0;count2<w;count2++){
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				}
				sb.append("\n");
				c = count+1;
					
			} for(int count2 = 0;count2<w;count2++){
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				} int count2 = 0; int count2 = 0; count2 0 count2<w count2 w count2++ count2++ count2 {
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				} {
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				} if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					} c % 2 == 0 c % 2 c 2 0 {
						sb.append("#");
						c++;
					} sb.append("#") sb.append sb "#" c++ c {
						sb.append(".");
						c++;
					} sb.append(".") sb.append sb "." c++ c sb.append("\n") sb.append sb "\n" c = count+1 c count+1 count 1 System.out.println(new String(sb)) System.out.println System.out System System.out new String(sb) sb.delete(0, sb.length()) sb.delete sb 0 sb.length() sb.length sb c = 0 c 0 String args[] args public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		// sb.append("");// ??????????????\???????????????
		int h, w, c;
		c = 0;// ?????¶??§???????????°

		while (true) {
			h = scan.nextInt();// ????????????
			w = scan.nextInt();// ?¨??????????
			// h??¨w?????¨??????0????????£?????¨??????????????????????????????
			if ((h == 0) & (w == 0)) {
				break;
			}
			//????????????????????????
			for(int count = 0;count<h;count++){
				//?¨??????????????????????
				for(int count2 = 0;count2<w;count2++){
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				}
				sb.append("\n");
				c = count+1;
					
			}

			System.out.println(new String(sb));
			// StringBuilder????????????????????????
			sb.delete(0, sb.length());
			c = 0;// ?????¶??§???????????°????????????
		}

	}
} public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		// sb.append("");// ??????????????\???????????????
		int h, w, c;
		c = 0;// ?????¶??§???????????°

		while (true) {
			h = scan.nextInt();// ????????????
			w = scan.nextInt();// ?¨??????????
			// h??¨w?????¨??????0????????£?????¨??????????????????????????????
			if ((h == 0) & (w == 0)) {
				break;
			}
			//????????????????????????
			for(int count = 0;count<h;count++){
				//?¨??????????????????????
				for(int count2 = 0;count2<w;count2++){
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				}
				sb.append("\n");
				c = count+1;
					
			}

			System.out.println(new String(sb));
			// StringBuilder????????????????????????
			sb.delete(0, sb.length());
			c = 0;// ?????¶??§???????????°????????????
		}

	}
} Main


import java.util.*;

public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		// sb.append("");// ??????????????\???????????????
		int h, w, c;
		c = 0;// ?????¶??§???????????°

		while (true) {
			h = scan.nextInt();// ????????????
			w = scan.nextInt();// ?¨??????????
			// h??¨w?????¨??????0????????£?????¨??????????????????????????????
			if ((h == 0) & (w == 0)) {
				break;
			}
			//????????????????????????
			for(int count = 0;count<h;count++){
				//?¨??????????????????????
				for(int count2 = 0;count2<w;count2++){
					if(c % 2 == 0){
						sb.append("#");
						c++;
					}else{
						sb.append(".");
						c++;
					}
				}
				sb.append("\n");
				c = count+1;
					
			}

			System.out.println(new String(sb));
			// StringBuilder????????????????????????
			sb.delete(0, sb.length());
			c = 0;// ?????¶??§???????????°????????????
		}

	}
}