#include <bits/stdc++.h>
using namespace std;
int main() {
  int H = 0;
  int W = 0;
  int i;
  int j;
  int check = 0;
  int a = 0;
  while (1) {
    cin >> H >> W;
    if (H == 0 && W == 0) goto EXIT;
    for (i = 0; i < H; i++) {
      for (j = 0; j < W; j++) {
        if (i % 2 == 0 && j % 2 == 0) cout << "#";
        if (i % 2 == 0 && j % 2 == 1) cout << ".";
        if (i % 2 == 1 && j % 2 == 0) cout << ".";
        if (i % 2 == 1 && j % 2 == 1) cout << "#";
      }
      cout << "\n";
    }
  }
EXIT:;
}
