#include <bits/stdc++.h>
using namespace std;
int main() {
  int H[10000], W[10000];
  for (int i = 0; i < 9999; i++) {
    cin >> H[i] >> W[i];
    if (H[i] == 0 && W[i] == 0) {
      break;
    }
  }
  for (int j = 0; j < 9999; j++) {
    if (H[j] == 0 && W[j] == 0) {
      break;
    }
    for (int m = 0; m < H[j]; m++) {
      if (W[j] == 1) {
        cout << "#" << endl;
        break;
      }
      if (m % 2 == 0) {
        for (int k = 0; k < W[j] / 2; k++) {
          cout << "#.";
        }
        cout << endl;
      } else if (m % 2 == 1) {
        for (int l = 0; l < W[j] / 2; l++) {
          cout << ".#";
        }
        cout << endl;
      }
    }
    cout << endl;
  }
  return 0;
}
