#include <bits/stdc++.h>
int main() {
  int n, m;
  while (scanf("%d %d", &n, &m), n + m) {
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++)
        if ((i + j) % 2 == 0)
          putchar('#');
        else
          putchar('.');
      puts("");
    }
  }
  return 0;
}
