#include "bits/stdc++.h"
using namespace std;


bool check(){
	int H, W;
	cin >> H >> W;
	vector<vector<int>> board(H, vector<int>(W));
	string s;
	int button = 0;
	for (int i = 0; i < H; i++)
	{
		cin >> s;
		for (int j = 0; j < W; j++)
		{
			if (s[j] == '#'){
				board[i][j] = 1;
				button++;
			}
		}
	}
	if (button == 0) return false;

	vector<vector<int>> dp(H, vector<int>(W));
	int turn = 0;
	int dk = 0;
	int dy[] {1, 0, -1, 0};
	int dx[] {0, 1, 0, -1};
	for (int t = 1; t < 4; t += 2){
		for (int i = 0; i < H; i++)
		{
			for (int j = 0; j < W; j++)
			{
				if (!board[i][j]) continue;
				for (int k = 0; k < 4; k++)
				{
					dk = k;
					int count = 1;
					int y = i;
					int x = j;
					turn++;

					while (true){
						int ny, nx;
						ny = y + dy[dk];
						nx = x + dx[dk];
						if (nx < 0 || ny < 0 || nx >= W || ny >= H || board[nx][nx] == 0 || dp[ny][nx] == turn){
							dk += t;
							if (dk >= 4) dk -= 4;
							ny = y + dy[dk];
							nx = x + dx[dk];
							if (nx < 0 || ny < 0 || nx >= W || ny >= H || board[nx][nx] == 0 || dp[ny][nx] == turn) break;
						}
						y = ny;
						x = nx;
						dp[y][x] = turn;
						count++;
					}
					if (count == button) return true;
				}
			}
		}
	}
	return false;
}


int main(){
	if (check()) cout << "YES" << endl;
	else cout << "NO" << endl;

}