

import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		//????????£????????????????????°?????????????????£?¨?
				Scanner sc = new Scanner(System.in);
		while(true){
			//???
			int H = sc.nextInt();
			//?¨?
			int W = sc.nextInt();
			//??\?????????0????????????
			if(H ==0 && W ==0){
				break;
			}
			//???????????¶???
			for(int i =1; i <=H; i++){
				//?¨?????????¶???
				String s = "";
				for(int j =1; j<=W; j++){
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				}
				System.out.println(s);
			}
		System.out.println("");
		}
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args){
		//????????£????????????????????°?????????????????£?¨?
				Scanner sc = new Scanner(System.in);
		while(true){
			//???
			int H = sc.nextInt();
			//?¨?
			int W = sc.nextInt();
			//??\?????????0????????????
			if(H ==0 && W ==0){
				break;
			}
			//???????????¶???
			for(int i =1; i <=H; i++){
				//?¨?????????¶???
				String s = "";
				for(int j =1; j<=W; j++){
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				}
				System.out.println(s);
			}
		System.out.println("");
		}
	}
} Main public static void main(String[] args){
		//????????£????????????????????°?????????????????£?¨?
				Scanner sc = new Scanner(System.in);
		while(true){
			//???
			int H = sc.nextInt();
			//?¨?
			int W = sc.nextInt();
			//??\?????????0????????????
			if(H ==0 && W ==0){
				break;
			}
			//???????????¶???
			for(int i =1; i <=H; i++){
				//?¨?????????¶???
				String s = "";
				for(int j =1; j<=W; j++){
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				}
				System.out.println(s);
			}
		System.out.println("");
		}
	} main {
		//????????£????????????????????°?????????????????£?¨?
				Scanner sc = new Scanner(System.in);
		while(true){
			//???
			int H = sc.nextInt();
			//?¨?
			int W = sc.nextInt();
			//??\?????????0????????????
			if(H ==0 && W ==0){
				break;
			}
			//???????????¶???
			for(int i =1; i <=H; i++){
				//?¨?????????¶???
				String s = "";
				for(int j =1; j<=W; j++){
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				}
				System.out.println(s);
			}
		System.out.println("");
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) while(true){
			//???
			int H = sc.nextInt();
			//?¨?
			int W = sc.nextInt();
			//??\?????????0????????????
			if(H ==0 && W ==0){
				break;
			}
			//???????????¶???
			for(int i =1; i <=H; i++){
				//?¨?????????¶???
				String s = "";
				for(int j =1; j<=W; j++){
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				}
				System.out.println(s);
			}
		System.out.println("");
		} true {
			//???
			int H = sc.nextInt();
			//?¨?
			int W = sc.nextInt();
			//??\?????????0????????????
			if(H ==0 && W ==0){
				break;
			}
			//???????????¶???
			for(int i =1; i <=H; i++){
				//?¨?????????¶???
				String s = "";
				for(int j =1; j<=W; j++){
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				}
				System.out.println(s);
			}
		System.out.println("");
		} int H = sc.nextInt(); H sc.nextInt() sc.nextInt sc int W = sc.nextInt(); W sc.nextInt() sc.nextInt sc if(H ==0 && W ==0){
				break;
			} H ==0 && W ==0 H ==0 H 0 W ==0 W 0 {
				break;
			} break; for(int i =1; i <=H; i++){
				//?¨?????????¶???
				String s = "";
				for(int j =1; j<=W; j++){
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				}
				System.out.println(s);
			} int i =1; int i =1; i 1 i <=H i H i++ i++ i {
				//?¨?????????¶???
				String s = "";
				for(int j =1; j<=W; j++){
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				}
				System.out.println(s);
			} {
				//?¨?????????¶???
				String s = "";
				for(int j =1; j<=W; j++){
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				}
				System.out.println(s);
			} String s = ""; s "" for(int j =1; j<=W; j++){
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				} int j =1; int j =1; j 1 j<=W j W j++ j++ j {
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				} {
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				} if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					} i % 2 ==0 i % 2 i 2 0 {
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					} if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						} j %2 ==0 j %2 j 2 0 {
							s += "#";
							//?¨?????\???°??????
						} s += "#" s "#" {
							s +=".";
						} s +="." s "." {
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					} if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						} j % 2==0 j % 2 j 2 0 {
							s +=".";
						//?¨?????\???°??????
						} s +="." s "." {
							s +="#";
						} s +="#" s "#" System.out.println(s) System.out.println System.out System System.out s System.out.println("") System.out.println System.out System System.out "" String[] args args public class Main {
	public static void main(String[] args){
		//????????£????????????????????°?????????????????£?¨?
				Scanner sc = new Scanner(System.in);
		while(true){
			//???
			int H = sc.nextInt();
			//?¨?
			int W = sc.nextInt();
			//??\?????????0????????????
			if(H ==0 && W ==0){
				break;
			}
			//???????????¶???
			for(int i =1; i <=H; i++){
				//?¨?????????¶???
				String s = "";
				for(int j =1; j<=W; j++){
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				}
				System.out.println(s);
			}
		System.out.println("");
		}
	}
} public class Main {
	public static void main(String[] args){
		//????????£????????????????????°?????????????????£?¨?
				Scanner sc = new Scanner(System.in);
		while(true){
			//???
			int H = sc.nextInt();
			//?¨?
			int W = sc.nextInt();
			//??\?????????0????????????
			if(H ==0 && W ==0){
				break;
			}
			//???????????¶???
			for(int i =1; i <=H; i++){
				//?¨?????????¶???
				String s = "";
				for(int j =1; j<=W; j++){
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				}
				System.out.println(s);
			}
		System.out.println("");
		}
	}
} Main


import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		//????????£????????????????????°?????????????????£?¨?
				Scanner sc = new Scanner(System.in);
		while(true){
			//???
			int H = sc.nextInt();
			//?¨?
			int W = sc.nextInt();
			//??\?????????0????????????
			if(H ==0 && W ==0){
				break;
			}
			//???????????¶???
			for(int i =1; i <=H; i++){
				//?¨?????????¶???
				String s = "";
				for(int j =1; j<=W; j++){
				//?¨??§??????????
					//????????¶??°??????
					if( i % 2 ==0){
					//?¨??????¶??°?????????
						if(j %2 ==0){
							s += "#";
							//?¨?????\???°??????
						}else{
							s +=".";
						}
						//???????\???°??????
					}else{
						//?¨??????¶??°??????
						if(j % 2==0){
							s +=".";
						//?¨?????\???°??????
						}else{
							s +="#";
						}
					}
				}
				System.out.println(s);
			}
		System.out.println("");
		}
	}
}