#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int h[256], w[256];
  int i = 0, t = 1;
  while (t == 1) {
    scanf("%d %d", &h[i], &w[i]);
    if (h[i] == 0 && w[i] == 0) t = 0;
    i++;
  }
  for (int j = 0; j < i - 1; j++) {
    printf("\n");
    for (int k = 0; k < h[j]; k++) {
      ;
      for (int l = 0; l < w[j]; l++) {
        if ((l + k) % 2 == 0) printf("#");
        if ((l + k) % 2 == 1) printf(".");
      }
      printf("\n");
    }
  }
  return 0;
}
