#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  bool isSharp = 1;
  char c;
  while (1) {
    scanf("%d %d\n", &h, &w);
    if (h == 0 && w == 0) return 0;
    for (int j = 0; j < h; j++) {
      for (int i = 0; i < w; i++) {
        if (isSharp)
          c = '#';
        else
          c = '.';
        isSharp = !isSharp;
        putchar(c);
      }
      putchar('\n');
      isSharp = !isSharp;
    }
    putchar('\n');
    isSharp = 1;
  }
}
