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

int main(){
    int h,w;
    cin>>h>>w;
    vector<vector<string>>vec(h,vector<string>(w));
    for (int i= 0; i < h; i++){
        for (int j = 0; j < w; j++){
        cin>>vec.at(i).at(j);

        cout<<vec<<endl;;
        cout<<"hello"<<endl;
        }
    }
    const vector<int>dx = {0,0,1,-1};
    const vector<int>dy = {1,-1,0,0};
    string s = "No";
    for (int i = 0; i < h; i++){
        for (int j = 0; j < w; j++){
            for (int d = 0; d < 4; d++){
            const int ni = i + dx.at(d);
            const int nj = j + dy.at(d);
            if (ni < 0 or i <= ni)continue;
            if (nj < 0 or j <= nj)continue;
            if (vec.at(i).at(j) == '#' and vec.at(ni).at(nj) == '#'){
                s = "Yes";
            }

            }
        }
    }
cout << s <<endl;
}