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