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