#include <bits/stdc++.h>
using namespace std;
int main() {
  for (;;) {
    int a, b;
    cin >> a >> b;
    if (a == 0 && b == 0) {
      break;
    } else {
      for (int i = 0; i < a / 2; i++) {
        for (int i = 0; i < b / 2; i++) {
          cout << "#.";
          if (b % 2 == 1) {
            cout << "#";
          }
        }
        cout << endl;
        for (int j = 0; i < b / 2; i++) {
          cout << ".#";
          if (b % 2 == 1) {
            cout << ".";
          }
        }
        cout << endl;
        if (a % 2 == 1) {
          for (int k = 0; k < b / 2; k++) {
            cout << "#.";
            if (b % 2 == 1) {
              cout << "#";
            }
          }
          cout << endl;
        }
      }
    }
  }
}
