#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  int a = 0, b = 0;
  while (1) {
    std::string line1 = "";
    std::string line2 = "";
    cin >> h >> w;
    if (h != 0 || w != 0) {
      if (h % 2 == 1) {
        h--;
        b = 1;
      }
      if (w % 2 == 1) {
        w--;
        a = 1;
      }
      for (int i = 0; i < w / 2; i++) {
        line1 += "#.";
        line2 += ".#";
      }
      if (a == 1) {
        line1 += "#";
        line2 += ".";
      }
      for (int j = 0; j < h / 2; j++) {
        cout << line1 << endl;
        cout << line2 << endl;
      }
      if (b == 1) {
        cout << line1 << endl;
      }
      cout << endl;
    } else {
      break;
    }
  }
  return 0;
}
