#include <bits/stdc++.h>
int main(void) {
  char buffer[256];
  int w[30], h[30];
  int counter = 0;
  while (1) {
    fgets(buffer, 256, stdin);
    sscanf(buffer, "%d %d", &w[counter], &h[counter]);
    if (w[counter] == 0 && h[counter] == 0) break;
    counter++;
  }
  int i, j, k;
  for (i = 0; i < counter; i++) {
    char mark[3] = "#.";
    int flag;
    for (j = 0; j < h[i]; j++) {
      if (j % 2 == 0)
        flag = 0;
      else
        flag = 1;
      for (k = 0; k < w[i]; k++) {
        printf("%c", mark[flag]);
        if (flag)
          flag--;
        else
          flag++;
      }
      putchar('\n');
    }
    putchar('\n');
  }
}
