 #include <iostream>
    using namespace std;
     
    int main() {
	int h,w;
	while(1){
		cin>> h >> w;
		if(h == 0 && w == 0){
			break;
		}
		 for (i=0; i<h/2; i++){
		 	for (j=0; j<w/2; j++ ){
		 		cout<<"#.";
		 	}
		 	if (w%2 == 1){
		 		cout<<"#";
		 	}
		 	cout<<endl;
		 	for (j=0; j<w/2; j++ ){
		 		cout<<".#";
		 	}
		 	if (w%2 == 1){
		 		cout<<".";
		 	}
		 	cout<<endl;
		 } 
		 if(h%2==1){
		 	for (j=0; j<w/2; j++ ){
		 		cout<<"#.";
		 	}
		 	if (w%2 == 1){
		 		cout<<"#";
		 	}
		 }
		 cout<<endl;
		 cout<<endl;
	}
    return 0;
    }