#include <bits/stdc++.h>

using namespace std;

int main(){

	int H,W;
	cin >> H >> W;
	
	string s[H][W];
	
	for(int i=0;i<H;i++){
		for(int j=0;j<W;j++){
			cin >> s[i][j];
		}
	}

	bool ans = true;

	for(int i=0;i<H;i++){
		for(int j=0;j<W;j++){
			if(s[i][j]=='#'){
				if(i-1>=0){bool up = s[i-1][j]=='#';}
				if(j-1>=0){bool left = s[[i][j-1]=='#';}
				if(i+1<H){bool down = s[i+1][j]=='#';}
				if(j+1<W){bool right = s[i][j+1]=='#';}
				
				if(up||left||down||right){continue;}
				else{
					bool ans = false;
					cour << "No" <<endl;
					return 0;
				}
			
			
			}
		}
	}
	
	if(ans){
		cout << "Yes" <<endl;
	}
	
	return 0;

}