#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 k = 1; k <= H[j]; k++) {
      for (int l = 1; l <= W[j]; l++) {
        int s = k + l;
        if (s % 2 == 0) {
          cout << "#";
        } else {
          cout << ".";
        }
      }
      cout << endl;
    }
  }
  return 0;
}
