#pragma region header
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(i, n) for (int i = 1; i <= (int)(n); i++)
#define rev(i, n) for(int i = (int)(n - 1); i >= 0; i--)
#define rev1(i, n) for(int i = (int)(n); i > 0; i--)
#define pb push_back
#define all(v) (v).begin(), (v).end()
#define resort(v) sort((v).rbegin(), (v).rend())
#define vi vector<int>
#define vvi vector<vector<int>>
#define vc vector<char>
#define vvc vector<vector<char>>
#define vb vector<bool>
#define vvb vector<vector<bool>>
using ll = long long;
using P = pair<int, int>;
/* ----------------よく使う数字や配列----------------- */
int dx[] = {1,0,-1,0};
int dy[] = {0,1,0,-1};
constexpr ll mod = 1e9+7;
constexpr ll inf = INT32_MAX/2;
constexpr ll INF = LLONG_MAX/2;
constexpr long double eps = DBL_EPSILON;
constexpr long double pi = 3.141592653589793238462643383279;
/* ----------------------end----------------------- */

/* --------------------テンプレート------------------ */
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
/* ----------------------end----------------------- */

/* --------------------ライブラリ-------------------- */
ll fact(int i) {       //階乗
    if (i == 0) return 1;
    return (fact(i - 1)) * i % mod;
}
ll gcd(ll a, ll b) {        //最大公約数
    if(b == 0) return a;
    return gcd(b, a % b); 
}
ll lcm(ll a, ll b) {      //最小公倍数
    return a * b / gcd(a, b);
}
int keta(ll n) {        //桁数を求める
    if(n == 0) return 1;
    int count = 0;
    while(n != 0) {
        n /= 10;
        count++;
    }
    return count;
}
ll ketasum(ll n) {    //各桁の和
    ll sum = 0;
    while(n != 0) {
        sum += n % 10;
        n /= 10;
    }
    return sum;
}
/* ----------------------end----------------------- */
#pragma endregion
signed main() { 
    int h,w;cin >> h >> w;
    vvb bo(h,vb(w));
    vector<P> v;
    rep(i, h) {
        rep(j, w) {
            char c;cin >> c;
            if(c=='#') {
                bo[i][j]=true;
                v.pb({i,j});
            }
            else bo[i][j]=false;
        }
    }
    bool ok = true;
    rep(i, v.size()) {
        rep(j, 4) {
            int x=v[i].first+dx[j],y=v[i].second+dy[j];
            if(x<0||x>=h||y<0||y>=w||!bo[x][y]) {
                // cout << i << endl;
                if(j==3) {
                    cout << "No" << endl;
                    return 0;
                }
                continue;
            }
            break;
        }
    }
    cout << "Yes" << endl;
    return 0;
}
#include<cmath>
#include<iostream>
#include<algorithm>
using namespace std;

int main(void) {
	int H, W;
	scanf("%d %d", &H, &W);
	string s[50];
	for (int i = 0; i < H; i++) {
		cin >> s[i];
	}
	for (int i = 0; i < H; i++) {
		for (int j = 0; j < W; j++) {
			bool paintable = false;
			if (s[i][j] != '#') continue;
			if (j != W - 1 && s[i][j + 1] == '#') paintable = true;
			if (j != 0     && s[i][j - 1] == '#') paintable = true;
			if (i != H - 1 && s[i + 1][j] == '#') paintable = true;
			if (i != 0     && s[i - 1][j] == '#') paintable = true;
			// cout << i << " " << j << " " << paintable << "\n";
			if (!paintable) {
				printf("No\n");
				return 0;
			}
		}
	}
	printf("Yes\n");
	return 0;
}
