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