#include <bits/stdc++.h>
int main(void) {
  int a, b, c, d, e[10000], f[10000], h, g, i, j;
  a = b = 1;
  h = g = 0;
  while (a != 0 && b != 0) {
    scanf("%d %d", &a, &b);
    e[h] = a;
    f[g] = b;
    ++g;
    ++h;
    j = h;
  }
  g = h = 0;
  for (i = 1; i < j; ++i) {
    for (c = 1; c <= e[g]; ++c) {
      if (c % 2 == 1) {
        for (d = 1; d <= f[h]; ++d) {
          if (d % 2 == 1) {
            printf("#");
          } else if (d % 2 == 0) {
            printf(".");
          }
        }
      } else if (c % 2 == 0) {
        for (d = 1; d <= f[h]; ++d) {
          if (d % 2 == 1) {
            printf(".");
          } else if (d % 2 == 0) {
            printf("#");
          }
        }
      }
      printf("\n");
    }
    printf("\n");
  }
  return (0);
}
