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