#include <bits/stdc++.h>
using namespace std;
int main() {
  int H[100], W[100], count, count1, odd;
  count = 0;
  count1 = 0;
  odd = 3;
  while (count < 300) {
    cin >> H[count] >> W[count];
    if (H[count] == 0 && W[count] == 0) break;
    count++;
    count1++;
  }
  for (count = 0; count < count1; count++) {
    for (int loopH = 0; loopH < H[count]; loopH++) {
      for (int loopW = 0; loopW < W[count]; loopW++) {
        if (odd % 2 == 1) {
          cout << "#";
        } else {
          cout << ".";
        }
        odd++;
      }
      odd++;
      cout << endl;
    }
    odd = 3;
    cout << endl;
  }
  return 0;
}
