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