#include <bits/stdc++.h>
using namespace std;
int main() {
  for (;;) {
    int H, W;
    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 j = 0; j < W / 2; j++) {
          cout << "#.";
        }
        cout << endl;
        for (int k = 0; k < W / 2; k++) {
          cout << ".#";
        }
        cout << endl;
      }
    }
    if (H % 2 == 0 && W % 2 == 1) {
      for (int l = 0; l < H / 2; l++) {
        for (int m = 0; m < (W - 1) / 2; m++) {
          cout << "#.";
        }
        cout << "#" << endl;
        for (int n = 0; n < (W - 1) / 2; n++) {
          cout << ".#";
        }
        cout << "." << endl;
      }
      cout << endl;
    }
    if (H % 2 == 1 && W % 2 == 0) {
      for (int o = 0; o < (H - 1) / 2; o++) {
        for (int p = 0; p < W / 2; p++) {
          cout << "#.";
        }
        cout << endl;
        for (int q = 0; q < W / 2; q++) {
          cout << ".#";
        }
        cout << endl;
      }
      for (int r = 0; r < W / 2; r++) {
        cout << "#.";
      }
      cout << endl;
    }
    if (H % 2 == 1 && W % 2 == 1) {
      for (int s = 0; s < (H - 1) / 2; s++) {
        for (int t = 0; t < (W - 1) / 2; t++) {
          cout << "#.";
        }
        cout << "#" << endl;
        for (int u = 0; u < (W - 1) / 2; u++) {
          cout << ".#";
        }
        cout << "." << endl;
      }
      for (int v = 0; v < (W - 1) / 2; v++) {
        cout << "#.";
      }
      cout << "#" << endl;
    }
    cout << endl;
  }
}
