#include<iostream>
using namespace std;
char c[55][55];
int main()
{
	int h,w;
	cin>>h>>w;
	for(int i=1;i<=h;i++) for(int j=1;j<=w;j++) cin>>c[i][j];
	for(int i=1;i<=h;i++)
		for(int j=1;j<=w;j++) 
			if(c[i][j]=='#')
				if(c[i-1][j]=='#'||c[i+1][j]=='#'||c[i][j-1]=='#'||c[i][j+1]=='#') continue;
				else
				{
					cout<<"No";
					return 0;
				}
	cout<<"Yes";
	return 0;
}