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