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

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

    }
    if(flag == 1)
    cout << "Yes" << endl ;
    else
    cout << "No" << endl ;

    return 0 ;
}