#include <set>
#include <list>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <complex>
#include <cstdlib>
#include <cstring>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <functional>
 
#define mp       make_pair
#define pb       push_back
#define all(x)   (x).begin(),(x).end()
#define rep(i,n) for(int i=0;i<(n);i++)
 
using namespace std;
 
typedef    long long          ll;
typedef    unsigned long long ull;
typedef    vector<bool>       vb;
typedef    vector<int>        vi;
typedef    vector<vb>         vvb;
typedef    vector<vi>         vvi;
typedef    pair<int,int>      pii;
 
const int INF=1<<29;
const double EPS=1e-9;
 
const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};
int main(int argc, char const *argv[]) {
	
	int H, W;
	cin >> H >> W;

	std::vector<string> map;
	for (int i = 0; i < H; ++i) {
		string temp;
		cin >> temp;
		map.push_back(temp);
	}

	int count = 0;
	for (int i = 0; i < H; ++i) {
		for (int j = 0; j < W; ++j) {
			if (map[i][j] == '#') {
				count++;
			}
		}
	}
	if (count % 2 != 0 || count == 0) {
		cout << "NO" << endl;
		return 0;
	}

	std::vector<std::vector<int> > color(H, std::vector<int>(W, 0));

	for (int dy = -H; dy < H; ++dy) {
		for (int dx = -W; dx < W; ++dx) {
			if (dy == 0 && dx == 0) continue;
			//初期化
			for (int i = 0; i < H; ++i) {
				for (int j = 0; j < W; ++j) {
					color[i][j] = 0;
				}
			}
			bool flag = true;
			for (int i = 0; i < H; ++i) {
				for (int j = 0; j < W; ++j) {
					int posx = j + dx;
					int posy = i + dy;
					if (color[i][j] != 0) continue;
					if (map[i][j] == '#') {
						if (posx >= W || posy >= H || posx < 0 || posy < 0) {
							flag = false;
							continue;
						}
						if (color[posy][posx] != 0) {
							flag = false;
						}
						if (map[posy][posx] == '.') {
							flag = false;
						}
						color[i][j] = 1;
						color[posy][posx] = -1;
					}
				}
			}
			if (flag) {
				cout << "YES" << endl;
				/*
				cout << "DEBUG :" << dx << "," << dy << endl;
				for (int i = 0; i < H; ++i) {
					for (int j = 0; j < W; ++j) {
						if (color[i][j] == 1) {
							cout << "r";
						} else if (color[i][j] == -1) {
							cout << "b";
						} else {
							cout << "_";						}
					}
					cout << endl;
				}
				*/
				
				return 0;
			}

		}
	}

	cout << "NO" << endl;

	return 0;
}