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