#include <bits/stdc++.h>
#pragma warning(disable : 4996)
int main(void) {
  int H;
  int W;
  int loop1;
  int loop2;
  while (1) {
    scanf("%d %d", &H, &W);
    if ((H == 0) && (W == 0)) {
      break;
    }
    for (loop1 = 0; loop1 < H; loop1++) {
      for (loop2 = 0; loop2 < W; loop2++) {
        if (((loop1 % 2) == 1) || (loop2 != 0)) {
          if (((loop2 % 2) == 1) || (loop2 != 0)) {
            printf("#");
          } else {
            printf(".");
          }
        } else {
          if (((loop2 % 2) == 1) || (loop2 != 0)) {
            printf(".");
          } else {
            printf("#");
          }
        }
      }
      printf("\n");
    }
    printf("\n");
  }
  return (0);
}
