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