#include <iostream>
#include <string>
#include <algorithm>

using namespace std;

int main() {
 string line;
 string rvs;
 int h, w;

 cin >> h >> w;

 for(int i = 0;i < w;i++) {
  if(i % 2 == 0) {
    line += ".";
  } else {
    line += "#";
  }
 }

 rvs = reverse(line.begin(), line.end());

 for(int i = 0;i < h;i++) {
  if(i % 2 == 0)
    cout << line << endl;
  else
    cout << rvs << endl;
 }

 return 0;
}