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