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