#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w, i;
  bool b = true;
  string ans = "", temp1 = "", temp2 = "";
  while (1) {
    cin >> h >> w;
    if (h == 0 && w == 0)
      break;
    else {
      for (i = 0; i < w; i++) {
        if (b)
          temp1 += "#";
        else
          temp1 += ".";
        b = !b;
      }
      b = false;
      for (i = 0; i < w; i++) {
        if (b)
          temp2 += "#";
        else
          temp2 += ".";
        b = !b;
      }
      b = true;
      for (i = 0; i < h; i++) {
        if (b)
          ans += temp1 + "\n";
        else
          ans += temp2 + "\n";
        b = !b;
      }
      cout << ans << endl;
      ans = "";
      temp1 = "";
      temp2 = "";
    }
  }
  return 0;
}
