#include <bits/stdc++.h>
using namespace std;
int main() {
  int N, M;
  cin >> N >> M;
  vector<vector<char>> maze(N, vector<char>(M));
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < M; j++) {
      cin >> maze[i][j];
    }
  }
  auto dfs = [&](int x, int y) {
    if (maze[x][y] == '#') {
      int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
      bool ch = false;
      for (int i = 0; i < 4; i++) {
        int nx = x + dx[i], ny = y + dy[i];
        if (0 <= nx && nx < N && 0 <= ny && ny < M && maze[nx][ny] == '#') {
          ch = true;
          x = nx;
          y = ny;
        }
      }
      if (ch) {
        maze[x][y] = '.';
      }
    }
    return;
  };
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < M; j++) {
      dfs(i, j);
    }
  }
  bool ans = true;
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < M; j++) {
      if (maze[i][j] == '#') {
        ans = false;
      }
    }
  }
  if (ans) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}
