#include <bits/stdc++.h>
int main(void) {
  char line[10];
  int H, W;
  int i, j;
  int sharpFirst = 0;
  while ((fgets(line, sizeof(line), stdin))) {
    sscanf(line, "%d %d", &H, &W);
    for (i = 1; i <= H; i++) {
      for (j = 1; j <= W; j++) {
        if ((i % 2) == (j % 2))
          printf("#");
        else
          printf(".");
      }
      printf("\n");
    }
    printf("\n");
  }
}
