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