#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int h[100], w[100];
  int k = 0;
  do {
    k = k + 1;
    cin >> h[k] >> w[k];
  } while (h[k] != 0 && w[k] != 0);
  cout << endl;
  k = 1;
  while (h[k] != 0 && w[k] != 0) {
    for (int i = 1; i <= h[k]; i++) {
      for (int j = 1; j <= w[k]; j++) {
        if ((i + j) % 2 == 0)
          cout << "#";
        else
          cout << ".";
      };
      cout << endl;
    };
    k = k + 1;
    cout << endl;
  }
  return 0;
}
