#include <bits/stdc++.h>
int main(void) {
  int H, W, i, ii;
  i = ii = 1;
  while (scanf("%d %d", &H, &W) == 2) {
    if (H == 0 && W == 0) break;
    while (i <= H) {
      while (ii <= W) {
        if (i % 2 == 1 && ii % 2 == 1) printf("#");
        if (i % 2 == 1 && ii % 2 == 0) printf(".");
        if (i % 2 == 0 && ii % 2 == 1) printf(".");
        if (i % 2 == 0 && ii % 2 == 0) printf("#");
        ii++;
      }
      printf("\n");
      ii = 1;
      i++;
    }
    printf("\n");
  }
  return 0;
}
