#include <bits/stdc++.h>
using namespace std;
void DrawEvenLine(int num) {
  for (int i = 1; i < num + 1; i++) {
    if (i % 2 == 1) {
      cout << ".";
    } else {
      cout << "#";
    }
    if (i == num) cout << endl;
  }
}
void DrawOddLine(int num) {
  for (int i = 1; i < num + 1; i++) {
    if (i % 2 == 1) {
      cout << "#";
    } else {
      cout << ".";
    }
    if (i == num) cout << endl;
  }
}
int main(int argc, char* argv[]) {
  int x, y;
  vector<pair<int, int>> variables;
  while (1) {
    cin >> x >> y;
    variables.push_back(make_pair(x, y));
    if (x == y && x == 0) break;
  }
  for (auto var : variables) {
    for (int i = 1; i < var.first + 1; i++) {
      if (i % 2 == 1) DrawOddLine(var.second);
      if (i % 2 == 0) DrawEvenLine(var.second);
    }
    cout << endl;
  }
  return 0;
}
