#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<vector<char>> v;
  for (int y = 0; y < H; ++y) {
    string s;
    cin >> s;
    vector<char> row;
    for (int x = 0; x < W; ++x) {
      char c = *(s.c_str() + x);
      row.push_back(c);
    }
    v.push_back(row);
  }
  auto black = [&v, &W, &H](int x, int y) {
    if (0 <= x && x < W && 0 <= y && y < H) {
      return v[y][x] == '#';
    }
    return false;
  };
  for (int y = 0; y < H; ++y) {
    for (int x = 0; x < W; ++x) {
      if (v[y][x] == '.') {
        continue;
      }
      if (black(x - 1, y) || black(x, y - 1) || black(x + 1, y) ||
          black(x, y + 1)) {
      } else {
        cout << v[y][x] << ", " << x << ", " << y << endl;
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
