#include <bits/stdc++.h>
using namespace std;
int dx[4] = {0, 1, 0, -1};
int dy[4] = {-1, 0, 1, 0};
int H, W;
char data[55][55];
bool check_around(int y, int x) {
  for (int i = 0; i < 4; i++) {
    int nx = x + dx[i];
    int ny = y + dy[i];
    if (nx < 0 || nx >= W || ny < 0 || ny >= H) continue;
    if (data[ny][nx] == '#') return true;
  }
  return false;
}
int main() {
  cin >> H >> W;
  int num_sharp = 0;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cin >> data[i][j];
      if (data[i][j] == '#') num_sharp++;
    }
  }
  bool result = true;
  bool empty = true;
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (data[i][j] == '#') {
        bool OK = check_around(i, j);
        if (OK) empty = false;
        if (!OK) {
          result = false;
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  if (empty) result = false;
  if (result)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
