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