#include <iostream>
#include <cstdio>
using namespace std;

int main() {
    bool label=true;
    int a, b;
    scanf("%d %d", &a, &b);
    char array[a][b]={};
    for (int i=0;i<a;i++){
            scanf("%s",array[i]);
    }
     for (int i=0;i<a;i++){
        for(int j=0;j<b;j++){
           // cout<<array[i][j];
            if(array[i][j]=='#'){
                if(array[i][j]!=array[i-1][j]&&array[i][j]!=array[i][j-1]&&array[i][j]!=array[i+1][j]&&array[i][j]!=array[i][j+1]){
                    return printf("No"), 0;
                }
                }
            }
        }
    
    //cout<<array[2][2];
    printf("Yes");
	return 0;
}
