#include<bits/stdc++.h>
using namespace std;
const int maxn=1e2+10;
long long Ans;
int f[maxn][maxn];
int main(){
	char ch;
	int n,m;
	cin>>n>>m;
	memset(f,-1,sizeof(f));
	for(register int i=1;i<=n;++i){
		for(register int j=1;j<=m;++j){
			cin>>ch;
			if(ch=='#')f[i][j]=0;
		}
	}int ans=0;
	for(register int i=1;i<=n;++i){
		for(register int j=1;j<=m;++j){
			if(!f[i][j]&&f[i][j-1]*f[i][j+1]*f[i-1][j]*f[i+1][j]!=0)ans=1;
		}
	}printf("%s",ans?"No":"Yes");
	cout<<endl;
	return 0;
}