#include <bits/stdc++.h>
int main() {
  int H, W, a[300], b[300], i = 0, N = 0;
  scanf("%d %d", &a[0], &b[0]);
  while (a[i] != 0 || b[i] != 0) {
    N++;
    i++;
    scanf("%d %d", &a[i], &b[i]);
  }
  for (i = 0; i <= N - 1; i++) {
    for (H = 1; H <= a[i]; H++) {
      if (H % 2 == 1) {
        if (b[i] % 2 == 0) {
          for (W = 1; W <= b[i] / 2; W++) printf("#.");
        }
        if (b[i] % 2 == 1) {
          for (W = 1; W <= (b[i] - 1) / 2; W++) {
            printf("#.");
          }
          printf("#");
        }
      }
      if (H % 2 == 0) {
        if (b[i] % 2 == 0) {
          for (W = 1; W <= b[i] / 2; W++) printf(".#");
        }
        if (b[i] % 2 == 1) {
          for (W = 1; W <= (b[i] - 1) / 2; W++) {
            printf(".#");
          }
          printf(".");
        }
      }
      printf("\n");
    }
  }
  return 0;
}
