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