#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, j, H, W;
  char inic, midc;
  while (1) {
    inic = 'o';
    midc = 'o';
    cin >> H >> W;
    if ((H == 0) && (W == 0)) break;
    for (i = 0; i < H; i++) {
      switch (inic) {
        case 'o':
          inic = '#';
          break;
        case '#':
          inic = '.';
          break;
        case '.':
          inic = '#';
          break;
      }
      cout << inic;
      midc = inic;
      for (j = 0; j < W; j++) {
        switch (midc) {
          case '#':
            midc = '.';
            break;
          case '.':
            midc = '#';
            break;
        }
        cout << midc;
      }
      cout << endl;
    }
    cout << endl;
  }
  return 0;
}
