#include<iostream>
using namespace std;
int main(){
  int i,j,H,W;
  int a=i/2;
  int b=j/2;
  while(true){
    cin >> H >> W;
    if(H==0 && W==0)break;
    for(i=1;i<=H;i++){
      if(i==2*a){
        for(j=1;j<=W;j++){
          if(j==2*b){
            cout << "#";
          }
          else if(j==2*b+1){
            cout << ".";
          }
        }
      }
      cout << endl;
      else if(i==2*a+1){
        for(j=1;j<=W;j++){
          if(j==2*b){
            cout << ".";
          }
          else if(j==2*b+1){
            cout << "#";
          }
        }
      }
      cout << endl;
    }
  cout << endl;
  }
}