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