#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int H, W;
  while (1) {
    cin >> H >> W;
    if (W == 0 && H == 0) break;
    for (int i = 0; i < H; i++) {
      for (int j = 0; j < W; j++) {
        if ((H + W) % 2 == 0)
          cout << "#";
        else
          cout << ".";
      }
      cout << endl;
    }
    cout << endl;
  }
  return 0;
}
