
#include <iostream>
#include <vector>

using namespace std;


int main() {
    int h, w;
    
    cin >> h >> w;

    vector<vector<char>> cam(h+2, vector(w+2, '.'));
    
    for(int i = 1; i < cam.size()-1; ++i)
        for(int j = 1; j < cam[i].size()-1; ++j)
            cin >> cam[i][j];

    bool yn = true;
    
    for(int i = 1; i < cam.size()-1; ++i)
        for(int j = 1; j < cam[i].size()-1; ++j)
            if(cam[i-1][j] == '.' && cam[i][j-1] == '.' &&
               cam[i+1][j] == '.' && cam[i][j+1] == '.') {
                yn = false;
                break;
            }
    
    cout << (yn ? "Yes" : "No") << endl;
    return 0;
}

