#include <bits/stdc++.h>
int main(void) {
  int H, W;
  int x, y;
  int flagx = 0;
  int flagy = 0;
  while (scanf("%d %d", &H, &W), (H + W) != 0) {
    for (y = 0; y < H; y++) {
      if (flagy == 0) {
        flagy = 1;
      } else {
        flagy = 0;
      }
      for (x = 0; x < W; x++) {
        if (x == 0) {
          if (flagy == 1) {
            printf("#");
            flagy = 0;
            flagx = 0;
          } else {
            printf(".");
            flagy = 1;
            flagx = 1;
          }
        } else {
          if (flagx == 1) {
            printf("#");
            flagx = 0;
          } else {
            printf(".");
            flagx = 1;
          }
        }
      }
      printf("\n");
    }
    printf("\n");
  }
  return (0);
}
