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