#include<algorithm>
#include<clocale>
#include<cmath>
#include<complex>
#include<csetjmp>
#include<csignal>
#include<cstdarg>
#include<cstddef>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<ctime>
#include<deque>
#include<iostream>
#include<istream>
#include<map>
#include<math.h>
#include<ostream>
#include<queue>
#include<set>
#include<sstream>
#include<string>
#include<vector>
using namespace std;
int n,k,dx[]={0,1,0,-1},dy[]={1,0,-1,0};
char c[100][100];
int main()
{
	cin>>n>>k;
	for (int i=0;i<n;i++)
		for (int j=0;j<k;j++)
			cin>>c[i][j];
	for (int i=0;i<n;i++)
		for (int j=0;j<k;j++){
			int f=0;
			for (int k=0;k<4;k++)
			if (i+dx[k]>=0&&i+dx[k]<n&&j+dy[k]>=0&&j+dy[k]<m&&c[i+dx[k]][j+dy[k]]=='.') f++;
			if (f==4){
				cout<<"No"<<endl;
				return 0;
			}
		}
	cout<<"Yes"<<endl;
	return 0;
}