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