#include <bits/stdc++.h>
using namespace std;
int main(void) {
  while (1) {
    int h = 0;
    int w = 0;
    cin >> h >> w;
    if ((h == 0) && (w == 0)) {
      break;
    }
    for (int i = 0; i < h; i++) {
      bool point = false;
      for (int j = 0; j < w; j++) {
        if (point == true) {
          cout << '.';
          point = false;
        } else {
          cout << '#';
          point = true;
        }
      }
      cout << endl;
    }
    cout << endl;
  }
  return 0;
}
