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