#include<cstdio>
#define maxn 55
using namespace std;
int n,m,a[maxn][maxn],fg[4][2]={{-1,0},{0,1},{1,0},{0,-1}};
char s[maxn];
bool check(int x,int y){
	for (int i=0;i<4;++i)
	if (a[x+fg[i][0]][y+fg[i][1]]) return 0;
	return 1;
}
int main()
{
	scanf("%d%d",&n,&m);
	for (int i=1;i<=n;++i){
		scanf("%s",s+1);
		for (int j=1;j<=m;++j) a[i][j]=s[j]=='#';
	}
	for (int i=1;i<=n;++i)
	for (int j=1;j<=m;++j) if (a[i][j]&&check(i,j)) {printf("No\n");return 0;}
	printf("Yes\n");
	return 0;
}