import java.util.Scanner;
class Main{
    int H,W,i,r;
    boolean x = true;
    public void solve(){
        Scanner sc = new Scanner(System.in);
        H = sc.nextInt();
        W = sc.nextInt();
        if(H == 0 && W == 0){
            x = false;
        }
        while(x == true){
            for(i = 0; i < H; i++){
                for(r = 0; r < W; r++){
                    if(i%2 == 0 && r%2 == 0 || i%2 == 1 && r%2 == 1){
                        System.out.print("#");
                    }else{
                        System.out.print(".");
                    }
                }
                System.out.println();
            }
            System.out.println();
            H = sc.nextInt();
            W = sc.nextInt();
            if(H == 0 && W == 0){
                x = false;
            }
        }
    }
    public static void main(String[] args){
        new Main().solve();
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz