#include <iostream>
#include <cmath>
#include <vector>
#include <map>
#include <iomanip>
#include <algorithm>
#include <sstream>
#include <string>
#include <math.h>
#include <set>
#include <deque>
#include <queue>
#include <list>
using namespace std;
typedef long long ll;
const int mod = 1000000007;

int main() {
    ios::sync_with_stdio(false);
    int h, w;
    cin >> h >> w;
    string s[h][w] = {};
    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] == "#" && s[i][j] != s[i - 1][j] && s[i][j] != s[i][j - 1] && s[i][j] != s[i][j + 1] && s[i][j] != s[i + 1][j]) {
                cout << "No";
                return 0;
            }
        }
    }
    cout << "Yes";
}
/*
*/
