#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  bool flag = true;
  cin >> H >> W;
  if (H == 0 && W == 0) {
    flag = false;
  }
  while (flag == true) {
    for (int i = 1; i <= H; i++) {
      if (i % 2 != 0) {
        for (int k = 0; k < W / 2; k++) {
          cout << "#.";
        }
      }
      if (i % 2 == 0) {
        for (int k = 0; k < W / 2; k++) {
          cout << ".#";
        }
      }
      cout << endl;
    }
    cin >> H >> W;
    if (H == 0 && W == 0) {
      flag = false;
    }
    cout << endl;
  }
  return 0;
}
