#include <bits/stdc++.h>
int main() {
  int h, w, H, W;
  int a = h % 2;
  int b = w % 2;
  int c = h / 2;
  int d = w / 2;
  while (1) {
    scanf("%d%d", &h, &w);
    if (h == 0 && w == 0) {
      break;
    } else if (a == 0) {
      if (b == 0) {
        for (H = 0; H < c; H++) {
          for (W = 0; W < d; W++) {
            printf("#.");
          }
          printf("\n");
          for (W = 0; W < d; W++) {
            printf(".#");
          }
          printf("\n");
        }
        printf("\n");
      } else {
        for (H = 0; H < c; H++) {
          for (W = 0; W < d; W++) {
            printf("#.");
          }
          printf("#\n");
          for (W = 0; W < d; W++) {
            printf(".#");
          }
          printf(".\n");
        }
        printf("\n");
      }
    } else {
      if (b == 0) {
        for (H = 0; H < c; H++) {
          for (W = 0; W < d; W++) {
            printf("#.");
          }
          printf("\n");
          for (W = 0; W < d; W++) {
            printf(".#");
          }
          printf("\n");
          for (W = 0; W < d; W++) {
            printf("#.");
          }
          printf("\n");
        }
        printf("\n");
      } else {
        for (H = 0; H < c; H++) {
          for (W = 0; W < d; W++) {
            printf("#.");
          }
          printf("#\n");
          for (W = 0; W < d; W++) {
            printf(".#");
          }
          printf(".\n");
          for (W = 0; W < d; W++) {
            printf("#.");
          }
          printf("#\n");
        }
        printf("\n");
      }
    }
  }
  return 0;
}
