#include <bits/stdc++.h>
int main() {
  int i, j, k;
  int H[99999], W[99999];
  for (i = 0; i < 99999; i++) {
    H[i] = 0;
    W[i] = 0;
  }
  i = 0;
  while (1) {
    scanf("%d %d", &H[i], &W[i]);
    if (H[i] == 0 && W[i] == 0) {
      break;
    }
    i++;
  }
  printf("\n");
  for (i = 0; i < 99999; i++) {
    if (H[i] == 0 && W[i] == 0) {
      break;
    }
    for (j = 0; j < H[i]; j++) {
      for (k = 0; k < W[i]; k++) {
        if ((j % 2 == 0 && k % 2 == 0) || (j % 2 == 1 && k % 2 == 1)) {
          printf("#");
        } else {
          printf(".");
        }
      }
      printf("\n");
    }
    printf("\n");
  }
  return 0;
}
