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