#include<iostream>
#include <algorithm>
using namespace std;
int main(){
    int h,w;
    while(1){
        cin >> h >> w;
        for(int i=0; i<h; i++){//heiht
            for(int j=0; j<w; j++){//width
                if(i%2!=0 && j%2!=0){//h???0??????,w???0??????,w???n??????,w???n?????? 
                    cout << "#";
				}else if(i%2==0 && j%2==0){
					cout << "#";
                }else{
                    cout << "??\";
                }
            }
            cout << endl;
        }
        cout << endl;
        
        if(h==0&&w==0){
            return 0;
        }
        
    }
    return 0;
}