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