#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  char s[51][51];
  scanf("%d%d", &h, &w);
  bool ans = true;
  for (int i = 0; i < h; i++) {
    scanf("%s", s[i]);
    for (int j = 0; j < w; j++) {
      bool ok = s[i][j] != '#';
      if (i > 0) ok |= s[i - 1][j] == '#';
      if (i < h - 1) ok |= s[i + 1][j] == '#';
      if (j > 0) ok |= s[i][j - 1] == '#';
      if (j > w - 1) ok |= s[i][j + 1] == '#';
      ans &= ok;
    }
  }
  if (ans)
    puts("Yes");
  else
    puts("No");
  return 0;
}
