#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  while (cin >> H >> W) {
    if (H == 0 && W == 0) {
      break;
    }
    for (int j = 0; j < H / 2; j++) {
      for (int i = 0; i < W / 2; i++) {
        cout << "#.";
      }
      if (W % 2 == 1) {
        cout << "#";
      }
      cout << endl;
      for (int i = 0; i < W / 2; i++) {
        cout << ".#";
      }
      if (W % 2 == 1) {
        cout << ".";
      }
      cout << endl;
    }
    if (H % 2 == 1) {
      for (int i = 0; i < W / 2; i++) {
        cout << "#.";
      }
      cout << "#";
      cout << endl;
    }
    cout << endl;
  }
  return 0;
}
