#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  char s[60][60];
  int dx[4] = {1, -1, 0, 0};
  int dy[4] = {0, 0, 1, -1};
  cin >> H >> W;
  for (int i = 0; i < W; i++) {
    scanf("%s", &s[i]);
  }
  bool can = true;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      bool found = false;
      for (int k = 0; k < 4; k++) {
        int i2 = i + dx[k];
        int j2 = j + dy[k];
        if (i2 >= 0 && i2 < H && j2 >= 0 && j2 < W && s[i2][j2] == '#') {
          found = true;
        }
      }
      if (!found) can = false;
    }
  }
  if (can)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
