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