#include <iostream>

using  namespace std;

int main (){
	
	int H,W
	


for(int s=0;s<1000;s++){
    cin>>H>>W;
    
	
	if(H%2==0 && W%2==0){
		for(int i=0;i<H/2;i++){
			for(int i1=0;i1<W/2;i1++){
				cout<<"#.";
			}
			cout<<endl;
			
			for(int i2=0;i2<W/2;i2++){
				cout<<".#";
			}
			cout<<endl;
		}
	}
	
	if(H%2!=0 && W%2!=0){
		for(int i=0;i<H/2;i++){
			for(int i1=0;i1<W/2;i1++){
				cout<<"#.";
			}
			cout<<"#";
			cout<<endl;
			
			for(int i2=0;i2<W/2;i2++){
				cout<<".#";
			}
			cout<<"."<<endl;
		}
		
		for(int i1=0;i1<W/2;i1++){
				cout<<"#.";
			}
		cout<<endl;
		
	}
	
	if(H%2==0 && W%2!=0){
		for(int i=0;i<H/2;i++){
			for(int i1=0;i1<W/2;i1++){
				cout<<"#.";
			}
			cout<<"#";
			cout<<endl;
			
			for(int i2=0;i2<W/2;i2++){
				cout<<".#";
			}
			cout<<"."<<endl;
		}
		
		cout<<endl;
	}

	if(H%2!=0 && W%2==0){
		for(int i=0;i<H/2;i++){
			for(int i1=0;i1<W/2;i1++){
				cout<<"#.";
			}
			cout<<endl;
			
			for(int i2=0;i2<W/2;i2++){
				cout<<".#";
			}
			cout<<endl;
		}
		
		for(int i1=0;i1<W/2;i1++){
				cout<<"#.";
			}
		cout<<endl;
		
	}
	
	if(H==0 && W==0){
		s=100000000;
	}
}
}
