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