#include <bits/stdc++.h>
using namespace std;
bool isEven(int n) {
  if (n % 2 == 0)
    return true;
  else
    return false;
}
void write_sh(int n) {
  for (int i = 0; i < n / 2; i++) {
    cout << "#.";
  }
  if (isEven(n)) {
    cout << endl;
  } else {
    cout << "#" << endl;
  }
}
void write_dot(int n) {
  for (int i = 0; i < n / 2; i++) {
    cout << ".#";
  }
  if (isEven(n)) {
    cout << endl;
  } else {
    cout << "." << endl;
  }
}
int main() {
  int H, W;
  while (cin >> H >> W) {
    if (H == 0 && W == 0) {
      break;
    } else {
      for (int i = 0; i < H / 2; i++) {
        write_sh(W);
        write_dot(W);
      }
      if (isEven(H + 1)) {
        write_sh(W);
      }
    }
  }
}
