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