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