#include<iostream>
using namespace std;
int main(){
int a,b;
cin >> a >> b;
char x[a][b];
for(int i=0;i<a;i++)
for(int j=0;j<b;j++)
cin >> x[i][j];
for(int i=0;i<a;i++)
for(int j=0;j<b;j++)
if(x[i][j]=='#' and x[i][j+1]!='#' and x[i][j-1]!='#' and x[i+1][j]!='#' and x[i-1][j]!='#'){
cout << "No";
return 0;
}
cout << "Yes";
return 0;
}