#include <bits/stdc++.h>
void printChessboard(unsigned int High, unsigned int Wide);
int main(int argc, const char* argv[]) {
  unsigned int w = 1, h = 1;
  while (!(h == 0 && w == 0)) {
    scanf("%d %d", &h, &w);
    if (!(h == 0 && w == 0)) {
      printChessboard(h, w);
    }
  }
  return 0;
}
void printChessboard(unsigned int High, unsigned int Wide) {
  int i, j;
  for (i = 0; i < High; i++) {
    for (j = 0; j < Wide; j++) {
      if ((i + j) % 2 == 0) {
        printf("#");
      } else {
        printf(" ");
      }
    }
    puts("");
  }
  puts("");
}
