#include <bits/stdc++.h>
using namespace std;
int main() {
  while (1) {
    double H, W;
    cin >> H >> W;
    if (H == 0 && W == 0) break;
    if (ceil(H / 2) == floor(H / 2)) {
      if (ceil(W / 2) == floor(W / 2)) {
        for (int a = 0; a < H / 2; ++a) {
          for (int b = 0; b < W / 2; ++b) {
            printf("#.");
          }
          printf("\n");
          for (int c = 0; c < W / 2; ++c) {
            printf(".#");
          }
          printf("\n");
        }
        printf("\n");
      } else {
        for (int a = 0; a < H / 2; ++a) {
          for (int b = 0; b < floor(W / 2); ++b) {
            printf("#.");
          }
          printf("#\n");
          for (int c = 0; c < floor(W / 2); ++c) {
            printf(".#");
          }
          printf(".\n");
        }
        printf("\n");
      }
    } else {
      if (ceil(W / 2) == floor(W / 2)) {
        for (int a = 0; a < floor(H / 2); ++a) {
          for (int b = 0; b < W / 2; ++b) {
            printf("#.");
          }
          printf("\n");
          for (int c = 0; c < W / 2; ++c) {
            printf(".#");
          }
          printf("\n");
        }
        for (int d = 0; d < W / 2; ++d) {
          printf("#.");
        }
        printf("\n");
      } else {
        for (int a = 0; a < floor(H / 2); ++a) {
          for (int b = 0; b < floor(W / 2); ++b) {
            printf("#.");
          }
          printf("#\n");
          for (int c = 0; c < floor(W / 2); ++c) {
            printf(".#");
          }
          printf(".\n");
        }
        for (int d = 0; d < floor(W / 2); ++d) {
          printf("#.");
        }
        printf("#\n");
      }
    }
  }
}
