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