#include <bits/stdc++.h>
void hyouzi(int, int);
int main() {
  int x, y, i;
  int mat1[300], mat2[300];
  int count;
  count = 0;
  while (1) {
    scanf("%d %d", &x, &y);
    if (x == 0 && y == 0) break;
    mat1[count] = x;
    mat2[count] = y;
    count++;
  }
  printf("\n");
  for (i = 0; i <= count; i++) {
    hyouzi(mat1[i], mat2[i]);
  }
  return 0;
}
void hyouzi(int x, int y) {
  int i, j;
  for (i = 0; i < x; i++) {
    if (i % 2 == 0) {
      for (j = 0; j < y; j++) {
        if (j % 2 == 0)
          printf("#");
        else
          printf(".");
      }
    } else {
      for (j = 0; j < y; j++) {
        if (j % 2 == 0)
          printf(".");
        else
          printf("#");
      }
    }
    printf("\n");
  }
  printf("\n");
}
