#include <bits/stdc++.h>
int main(void) {
  int H, W;
  int i, j, k, count;
  int a[100][2];
  for (count = 0;; count++) {
    scanf("%d %d", &H, &W);
    if (H == 0 && W == 0) {
      break;
    }
    a[count][0] = H;
    a[count][1] = W;
  }
  for (i = 0; i < count; i++) {
    for (j = 0; j < a[i][0]; j++) {
      for (k = 0; k < a[i][1]; k++) {
        if ((i + j) % 2 == 0) {
          printf("#");
        } else {
          printf(".");
        }
      }
      printf("\n");
    }
    printf("\n");
  }
  return 0;
}
