#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  string s[H][W], S;
  for (int i = 0; i < H; i++) {
    cin >> S;
    for (int j = 0; j < W; j++) {
      s[i][j] = S[j];
    }
  }
  string a, b, c, d, e;
  bool flag = false;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      a = s[i][j];
      if (a == "#") {
        if (i == 0)
          d = ".";
        else
          d = s[i - 1][j];
        if (i == H - 1)
          e = ".";
        else
          e = s[i + 1][j];
        if (j == 0)
          b = ".";
        else
          b = s[i][j - 1];
        if (j == W - 1)
          c = ".";
        else
          c = s[i][j + 1];
        if (d == "#" || e == "#" || c == "#" || b == "#") break;
        flag = true;
      }
    }
    if (flag) break;
  }
  if (flag)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
  return 0;
}
