#include<stdio.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)
          pritnf("#");
          flagx = 0;
        } else {
          printf(".");
          flagx = 1;
        }
      }
    }
  printf("\n");
  }
  printf("\n");

  return (0);
}