#include "bits/stdc++.h"
using namespace std;
int main()
{
	int i,j,n,m;
	char str[51][51]={0};
	scanf("%d %d",&n,&m);
	for(i=0;i<n;i++)
	{
		scanf("%s",str[i]);
	}
	for(i=0;i<n;i++)
	{
		for(j=0;j<m;j++)
		{
			if(str[i][j]!='#')
			{
				continue;
			}
			if(str[i-1][j]!='#'&&str[i][j-1]!='#'&&str[i+1][j]!='#'&&str[i][j+1]!='#')
			{
				printf("No\n");
				return 0;
			}
		}
	}
	printf("Yes\n");
	return 0;
}