#include <bits/stdc++.h>
using namespace std;
constexpr int MOD = 1000000007;
template <class T>
inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
void print(const std::vector<int> &v) {
  std::for_each(v.begin(), v.end(), [](int x) { std::cout << x << " "; });
  std::cout << std::endl;
}
const int dy[4] = {-1, 0, 0, 1};
const int dx[4] = {0, -1, 1, 0};
int main() {
  int H;
  int W;
  vector<vector<char>> s(H + 1, vector<char>(W + 1));
  for (long long i = 0; i < (long long)H; i++) {
    for (long long j = 0; j < (long long)W; j++) {
      cin >> s[i][j];
    }
  }
  for (long long i = 0; i < (long long)H - 1; i++) {
    i++;
    for (long long j = 0; j < (long long)W - 1; j++) {
      j++;
      if (s[i][j] == '.') {
        continue;
      }
      int cnt = 0;
      for (long long k = 0; k < (long long)4; k++) {
        if (s[i + dx[k]][j + dy[k]] == '#') {
          cnt++;
        }
      }
      if (cnt == 0) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
}
