#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 (j + 2 == W) cout << "#";
      }
      cout << endl;
    }
    if (H != 1 && W == 1) {
      for (int i = 1; i < H; i += 2) {
        cout << "#" << endl << "." << endl;
        if (i + 2 == H) cout << "#" << endl;
      }
    }
    for (int i = 1; i < H; i += 2) {
      for (int j = 1; j < W; j += 2) {
        cout << "#"
             << ".";
        if (j + 2 == W) cout << "#";
        cout << endl;
      }
      for (int j = 1; j < W; j += 2) {
        cout << "."
             << "#";
        if (j + 2 == W) cout << ".";
        cout << endl;
      }
      if (i + 2 == H) {
        for (int j = 1; j < W; j += 2) {
          cout << "#"
               << ".";
          if (j + 2 == W) cout << "#";
          cout << endl;
        }
      }
    }
    cout << endl;
  }
  return 0;
}
