#include <bits/stdc++.h>
#pragma warning(disable : 4996)
using namespace std;
using ld = long double;
template <class T>
using Table = vector<vector<T>>;
const ld eps = 1e-9;
int main() {
  int H, W;
  cin >> H >> W;
  for (int i = 0; i < H; ++i) {
    for (int j = 0; j < W; ++j) {
      if ((i + j) % 2)
        cout << '.';
      else
        cout << "#";
    }
    cout << endl;
  }
  return 0;
}
