#include <bits/stdc++.h>
int main() {
  int n, m;
  bool f;
  while (1) {
    scanf("%d%d", &n, &m);
    f = true;
    if (n == 0) return 0;
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        if (f) {
          printf("#");
          f = false;
        } else {
          printf(".");
          f = true;
        }
      }
      printf("\n");
    }
    printf("\n");
  }
}
