#include <bits/stdc++.h>
using namespace std;
int dx[4] = {0, -1, 0, 1};
int dy[4] = {-1, 0, 1, 0};
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> S;
  for (int i = 0; i < H; ++i) {
    string str;
    cin >> str;
    S.push_back(str);
  }
  vector<vector<char>> ans(H, vector<char>(W, '.'));
  for (int i = 0; i < H; ++i) {
    for (int j = 0; j < W; ++j) {
      for (int k = 0; k < 4; ++k) {
        int ni = i + dx[k], nj = j + dy[k];
        if (ni < 0 || ni >= H || nj < 0 || nj >= W) continue;
        if (S[i][j] == '#' && S[ni][nj] == '#') ans[i][j] = ans[ni][nj] = '#';
      }
    }
  }
  bool can = true;
  for (int i = 0; i < H; ++i) {
    for (int j = 0; j < W; ++j) {
      if (S[i][j] != ans[i][j]) {
        can = false;
        break;
      }
    }
  }
  if (can)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
