#include<iostream>
using namespace std;

char grid[60][60];
int H, W;
bool flag;

int main(){
  for(int i = 1; i <= H; i++){
    for(int j = 1; j <= W; j++) {
      cin >> grid[i][j];
    }
  }

  frag = false;
  for(int i = 1; i <= H; i++){
    for(int j = 1; j <= W; j++) {
      if(grid[i][j] == '#' && grid[i-1][j] != '#' && grid[i+1][j] != '#' && grid[i][j-1] != '#' && grid[i][j+1] != '#' ) flag = true;
    }
  }
  if(!flag){
    cout << "Yes" <<endl;
  }else{
    cout << "No" << endl;
  }

}
