#include <bits/stdc++.h>
int main() {
  int h, w, i, j, flag;
  scanf("%d %d", &h, &w);
  char buf[h][w];
  for (i = 0; i < h; i++) {
    for (j = 0; j < w; j++) {
      scanf("%c", &buf[i][j]);
    }
  }
  for (i = 0, flag = 0; i < h; i++) {
    for (j = 0; j < w; j++) {
      if (buf[i][j] == '.') continue;
      if (j != 0 && buf[i][j - 1] == '#') continue;
      if (j != w - 1 && buf[i][j + 1] == '#') continue;
      if (i != 0 && buf[i - 1][j] == '#') continue;
      if (i != h - 1 && buf[i + 1][j] == '#') continue;
      flag = 1;
      break;
    }
    if (flag) break;
  }
  printf("%s", flag ? "No" : "Yes");
  return 0;
}
