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