#include <bits/stdc++.h>
int main(void) {
  int i, j, wide, height;
  int h[10000], w[10000];
  i = 1;
  while (1) {
    scanf("%d %d", &h[i], &w[i]);
    if (h[i] == 0 && w[i] == 0) {
      break;
    }
    i++;
  }
  for (j = 1; j < i; j++) {
    for (height = 1; height <= h[j]; height++) {
      for (wide = 1; wide <= w[j]; wide++) {
        if (wide % 2 == 0) {
          printf("#");
        } else {
          printf(".");
        }
      }
      printf("\n");
    }
    printf("\n");
  }
  return 0;
}
