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

int main(){
    int h,w;
    cin >> h >> w;
    vector<string>s(h+2, string(w+2, '.'));
    for(int i = 1; i <= h; i++){
        for(int j = 1; j <= w; j++){
            cin >> s[i][j];
        }
    }

    vector<vector<int>> mx1(h + 2, vector<int>(w + 2, 0));
    for(int i = 1; i <= h; i++){
        for(int j = 1; j <= w; j++){
            if(s[i][j] == '#') mx1[i][j] = mx1[i - 1][j - 1] + 1;
        }
    }
    vector<vector<int>> mx2(h + 2, vector<int>(w + 2, 0));
    for(int i = 1; i <= h; i++){
        for(int j = w; j >= 1; j--){
            if(s[i][j] == '#') mx2[i][j] = mx2[i - 1][j + 1] + 1;
        }
    }
    vector<vector<int>> mx3(h + 2, vector<int>(w + 2, 0));
    for(int i = h; i >= 1; i--){
        for(int j = 1; j <= w; j++){
            if(s[i][j] == '#') mx3[i][j] = mx3[i + 1][j - 1] + 1;
        }
    }
    vector<vector<int>> mx4(h + 2, vector<int>(w + 2, 0));
    for(int i = h; i >= 1; i--){
        for(int j = w; j >= 1; j--){
            if(s[i][j] == '#') mx4[i][j] = mx4[i + 1][j + 1] + 1;
        }
    }

    vector<vector<int>> imos1(h + 2, vector<int>(w + 2, 0));
    vector<vector<int>> imos2(h + 2, vector<int>(w + 2, 0));
    for(int i = 1; i <= h; i++){
        for(int j = 1; j <= w; j++){
            int l = min({mx1[i][j], mx2[i][j], mx3[i][j], mx4[i][j]}) - 1;
            if(l <= 0) continue;
            imos1[i - l][j - l]++;
            imos1[i + l + 1][j + l + 1]--;
            imos2[i - l][j + l]++;
            imos2[i + l + 1][j - l - 1]--;
        }
    }

    for(int i = 1; i < h + 2; i++){
        for(int j = 1; j <= w; j++){
            imos1[i][j] += imos1[i - 1][j - 1];
            imos2[i][j] += imos2[i - 1][j + 1];
        }
    }

    bool same = true;
    for(int i = 1; i <= h; i++){
        for(int j = 1; j <= w; j++){
            if(s[i][j] == '#' && imos1[i][j] + imos2[i][j] == 0){
                same = false;
            }
        }
    }
    
    cout << (same ? "Yes" : "No") << endl;
}