#include <bits/stdc++.h>
int main() {
  int i, j, k, a = 0, count, H[300], W[300];
  do {
    scanf("%d%d", &H[a], &W[a]);
    if (H[a] == 0 && W[a] == 0) {
      break;
    }
    a++;
  } while (1);
  for (i = 0; i <= a; i++) {
    for (j = 0; j < H[i]; j++) {
      if (j % 2 == 0) {
        count = 0;
      } else {
        count = 1;
      }
      for (k = 0; k < W[i]; k++) {
        (count % 2 == 0) ? printf("#") : printf(".");
        count++;
      }
      printf("\n");
    }
    printf("\n");
  }
  return 0;
}
