#include <bits/stdc++.h>
int main() {
  int h, w, i, t, r = 1, j = 1;
  while (1) {
    scanf("%d %d", &h, &w);
    if (h == 0 && w == 0) break;
    for (i = 0; i < h; i++) {
      j = r;
      for (t = 0; t < w + 1; t++) {
        if ((j % 2) == 1) printf("#");
        if ((j % 2) == 0) printf(".");
        j++;
      }
      printf("\n");
      r++;
    }
    printf("\n");
  }
  return 0;
}
