#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int H, W;
  char S = '#', G = '.';
  while (1) {
    int e = 1;
    cin >> H >> W;
    for (int a = 0; a < H; a++) {
      for (int b = 0; b < W; b++) {
        if (e % 2)
          cout << S;
        else
          cout << G;
        e++;
      }
      cout << endl;
    }
    if (W == 0 || H == 0) break;
    cout << endl;
  }
  return 0;
}
