#include <bits/stdc++.h>
int main(void) {
  int i, j, w = 0, h = 301;
  while (w != 0 || h != 0) {
    scanf("%d %d", &w, &h);
    for (i = 0; i < w; i++) {
      for (j = 0; j < h; j++) {
        if ((i + j) % 2 == 0)
          printf("#");
        else
          printf(".");
      }
      printf("\n");
    }
    printf("\n");
  }
  return 0;
}
