#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  int i, j;
  while (1) {
    char fig1[301] = {0};
    char fig2[301] = {0};
    cin >> H >> W;
    if (H == 0 && W == 0) break;
    for (i = 0; i < W; i += 2) {
      fig1[i] = '#';
    }
    for (i = 1; i < W; i += 2) {
      fig1[i] = '.';
    }
    for (i = 0; i < W; i += 2) {
      fig2[i] = '.';
    }
    for (i = 1; i < W; i += 2) {
      fig2[i] = '#';
    }
    for (i = 0; i < H / 2 + 1; i++) {
      cout << fig1 << endl;
      if (i != H / 2) {
        cout << fig2 << endl;
      }
    }
    cout << endl;
  }
  return 0;
}
