#include <iostream>
#include <string>
using namespace std ;

int main()
{
    bool flag = 1 ;
    int H , W ;
    cin >> H >> W ;
    string Pic[W+2];
    string frame;
    for(int i = 0 ; i < H+2 ; i++)
        frame += "." ;
    Pic[0] = frame ;
    Pic[W+1] = frame ;

    for(int i = 1 ; i <= H ; i++)
    {
        cin >> Pic[i] ;
        Pic[i] = "." + Pic[i] + "." ;
    }

    for(int i = 1 ; i <= W ; i++)
    {
        for(int j = 1 ; j <= H ; j++)
        {
            if(Pic[i][j] == "#")
            {
                if(Pic[i+1][j] == "#" || Pic[i-1][j] == "#" || Pic[i][j+1] == "#" || Pic[i][j-1] == "#")
                {
                flag = 1 ;
                }
                else
                {
                cout << "No" << endl ;
                return 0;
                }
            }
        }
    }
    if(flag == 1)
    cout << "Yes" << endl ;
    else
    cout << "No" << endl ;

    return 0 ;
}