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