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