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