#include<bits/stdc++.h>
#define rep(i,n)for(int i=0;i<n;++i)
#include<string>
#include<vector>
using namespace std;
typedef long long ll;
typedef pair<int, int>P;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
//max=({});
//条件式が真ならwhileの中身を回し続ける
//printf("%d\n", ans);

//pairの入力
//vector<pair<ll, ll>>work(n);
//rep(i, n) {
//	ll a, b;
//	cin >> a >> b;
//	work[i] = make_pair(a, b);
//}

int g[15][15];
const int INF = 1001001001;
const int dx[4] = { -1,0,1,0 };
const int dy[4] = { 0,-1,0,1 };

//最大公約数
ll gcd(ll x, ll y) {
	return y ? gcd(y, x % y) : x;
}

ll lcm(ll x, ll y) {
	if (x == 0 || y == 0)return 0;
	return (x / gcd(x, y) * y);
}

//素因数分解
vector<pair<ll, int>>factorize(ll n) {
	vector<pair<ll, int>>res;
	for (ll i = 2;i * i <= n;++i) {
		if (n % i)continue;
		res.emplace_back(i, 0);
		while (n % i == 0) {
			n /= i;
			res.back().second++;
		}
	}
	if (n != 1)res.emplace_back(n, 1);
	return res;
}

int dp[1010][1010];
int bingo[3][3];
bool flag[3][3];
int I[100][20];

int main() {
	int h, w;
	cin >> h >> w;
	bool flag = true;
	rep(i, h) {
		rep(j, w) {
			char s[i][j];
			cin >> s[i][j];
		}
	}
	rep(i, h) {
		rep(j, w) {
			if (s[i][j] == '#') {
				rep(k, 4) {
					int flag2 = 0;
					if (s[i + dx[k]][j + dy[k]] == '#')flag2++;
				}
				if (flag2 == 0)flag = false;
			}
		}
	}
	if (flag)puts("Yes");
	else puts("No");
	return 0;
}
