#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W, x;
  string a[300];
  string b[300];
  cin >> H >> W;
  while (!(H == 0 && W == 0)) {
    for (int i = 0; i < 150; i++) {
      a[i * 2] = "#";
      a[i * 2 + 1] = ".";
      b[i * 2] = ".";
      b[i * 2 + 1] = "#";
    }
    a[300] = "#";
    b[300] = ".";
    x = H / 2;
    for (int j = 0; j < x; j++) {
      for (int k = 0; k < W; k++) {
        cout << a[k];
      }
      cout << "\n";
      for (int l = 0; l < W; l++) {
        cout << b[l];
      }
      cout << "\n";
    }
    if (W % 2 == 1) {
      for (int m = 0; m < W; m++) {
        cout << a[m];
      }
      cout << "\n";
      cin >> H >> W;
    }
  }
  return 0;
}
