#include<iostream>
#include<algorithm>
using namespace std;
int main()
{
	int h,w;
	cin>>h>>w;
	string s[52];
	for(int i=0;i<h;i++) cin>>s[i];
	for(int i=0;i<h;i++)
	for(int j=0;j<=w;j++)
	{
		if(a[i][j]=='#')
		if(i!=0){if(a[i-1][j]=='#')continue;}
		if(i!=h-1){if(a[i+1][j]=='#')continue;}
		if(j!=0){if(a[i][j-1]=='#')continue;}
		if(j!=w-1){if(a[i][j+1]=='#')continue;}
		cout<<"No";
		return 0;
	}
	cout<<"Yes";
}