#include <iostream>
#include<vector>
#include<algorithm>
#include<string>
using namespace std;

int main(){
    int h,w;
    cin >> h >> w;

    string s[h];

    for(int i=0;i<h;i++){
        cin >> s[i];
    }

    bool ans = false;

    for(int y=0;y<h;y++){
        for(int x=0;x<w;x++){

            if(s[y][x]=='#'){
                int y_up = y+1;
                int y_down = y-1;
                int x_up = x+1;
                int x_down = x-1;
                
                if(x_up<w && s[y][x_up]=='#'){
                    ans = true;
                    break;
                }
                if(x_down>0 && s[y][x_down]=='#'){
                    ans = true;
                    break;
                }
                if(y_up<h && s[y_up][x]=='#'){
                    ans = true;
                    break;
                }
                if(y_down>0 && s[y_down][x]=='#'){
                    ans = true;
                    break;
                }
        }

        if(ans){
            break;
        }
    }
    if(ans) cout << "Yes" << endl;
    else cout << "No" << endl;
}