#include <bits/stdc++.h>
using namespace std;
using Graph = vector<vector<int>>;
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
const long long INF = 1LL << 60;
long long dp[100010];
long long h[100010];
int dx[4] = {0, -1, 0, 1};
int dy[4] = {1, 0, -1, 0};
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> S;
  string s;
  for (int i = 0; i < (int)(h); i++) {
    cin >> s;
    S.push_back(s);
  }
  bool can = true;
  for (int i = 0; i < (int)(h); i++) {
    for (int j = 0; j < (int)(w); j++) {
      if (S[i][j] == '#') {
        for (int k = 0; k < (int)(4); k++) {
          int x = j + dx[k];
          int y = i + dy[k];
          if (x < 0 || x >= w) continue;
          if (y < 0 || y >= h) continue;
          if (S[y][x] == '#') {
            can = true;
            break;
          } else if (S[y][x] != '#')
            can = false;
        }
      } else
        continue;
    }
  }
  if (can)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
