#include "bits/stdc++.h"

using namespace std;
using ll = long long;
const double pi = acos(-1);
#define FOR(i,a,b) for (ll i=(a),__last_##i=(b);i<__last_##i;i++)
#define RFOR(i,a,b) for (ll i=(b)-1,__last_##i=(a);i>=__last_##i;i--)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define __GET_MACRO3(_1, _2, _3, NAME, ...) NAME
#define rep(...) __GET_MACRO3(__VA_ARGS__, FOR, REP)(__VA_ARGS__)
#define rrep(...) __GET_MACRO3(__VA_ARGS__, RFOR, RREP)(__VA_ARGS__)
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v) {
	REP(i, v.size()) { if (i)os << " "; os << v[i]; }return os;
}
template<typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v) {
	REP(i, v.size()) { if (i)os << endl; os << v[i]; }return os;
}

const ll INF = 1LL << 60;
ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;

#define int long long

inline void my_io() {

	std::ios::sync_with_stdio(false);

	std::cin.tie(0);

	cout << fixed << setprecision(16);

	//cout << setprecision(10) << scientific << ans << endl;
}

signed main() {
	ll h, w;
	
	cin >> h >> w;

	vector<string> v(h);
	bool flag = false;

	REP(i, h) {
		cin >> v[i];
		if (!flag) {
			REP(j, w) {
				if (v[i][j] == '#') {
					flag = true;
					break;
				}
			}
		}
	}

	if (!flag) {
		cout << "NO" << endl;
		return 0;
	}

	REP(i, h) {
		REP(j, w) {
			if (i == 0 && j == 0) {
				continue;
			}

			vector<string> vv = v;
			flag = true;

			REP(k, h) {
				REP(l, w) {
					if (vv[k][l] == '#') {
						if (k + i < h && l + j < w && vv[k + i][l + j] == '#') {
							vv[k][l] = 'R';
							vv[k + i][l + j] = 'B';
						}
						else {
							flag = false;
							break;
						}
					}
				}
				if (!flag) {
					break;
				}
			}

			if (flag) {
				cout << "YES" << endl;
				return 0;
			}
		}
	}

	cout << "NO" << endl;
}