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