#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
const int mod = 1e9 + 7;
int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};
int main() {
  int h, w;
  cin >> h >> w;
  char s[55][55];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == '#') {
        int flag = 0;
        queue<pair<int, int> > que;
        que.push(pair<int, int>(i, j));
        while (que.size()) {
          pair<int, int> xy = que.front();
          que.pop();
          s[xy.first][xy.second] = '.';
          for (int k = 0; k < 4; k++) {
            int nx = xy.second + dx[k], ny = xy.first + dy[k];
            if (nx < 0 || w <= nx || ny < 0 || h <= ny || s[ny][nx] != '#')
              continue;
            que.push(pair<int, int>(ny, nx));
            flag = 1;
          }
        }
        if (flag == 0) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
