#include <bits/stdc++.h>
using namespace std;
const int maxn = 60;
int h, w, dirx[4] = {1, -1, 0, 0}, diry[4] = {0, 0, 1, -1};
string s[maxn];
bool check;
int main() {
  cin >> h >> w;
  for (int i = 0; i < h; i++) cin >> s[i];
  for (int i = 0; i < h; i++) {
    for (int j = 0, temp; j < w; j++) {
      if (s[i][j] == '.') {
        continue;
      }
      check = false;
      for (int k = 0, x, y; k < 4; k++) {
        x = dirx[k] + i;
        y = diry[k] + j;
        if (x < 0 || x >= h || y < 0 || y >= w) {
          continue;
        }
        if (s[x][y] == '#') {
          check = true;
        }
      }
      if (!check) {
        break;
      }
    }
  }
  if (check) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}
