#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int h = -1, w = -1;
  while (h != 0 && w != 0) {
    cin >> h >> w;
    for (int i = 0; i < h; i++) {
      if (i == 0 || i % 2 == 0) {
        for (int s = 0; s < w; s++) {
          if (s == 0 || s % 2 == 0) {
            cout << "#";
          } else {
            cout << ".";
          }
        }
      } else {
        for (int s = 0; s < w; s++) {
          if (s == 0 || s % 2 == 0) {
            cout << ".";
          } else {
            cout << "#";
          }
        }
      }
      cout << endl;
    }
    cout << endl;
  }
  cout << endl;
  return 0;
}
