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