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