#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using vb = vector<bool>;
using vvb = vector<vb>;
using vi = vector<int>;
using vvi = vector<vi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
const double PI = acos(-1);
const double EPS = 1e-10;
const ll MOD = 1e9 + 7;
void cioacc() {
  cin.tie(0);
  ios::sync_with_stdio(false);
}
int main() {
  int h, w;
  while (cin >> h >> w, h) {
    bool f = true;
    for (ll i = (0); i < (ll)(h); ++i) {
      for (ll j = (0); j < (ll)(w); ++j) {
        cout << (f ? '#' : '.');
        f = !f;
      }
      f = !f;
      puts("");
    }
    puts("");
  }
}
