#include <iostream>
#include <math.h>
#include <algorithm>
#include <vector>
#include <numeric>
#include <string>
using namespace std;
const double PI = acos(-1.0);
const string alp = "abcdefghijklmnopqrstuvwxyz";
const string ALP = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define SUM(c) accumulate((c).begin(),(c).end(),0)
#define Yn(b) puts(b?"Yes":"No")
#define YN(b) puts(b?"YES":"NO")

int main(){
  string s[50];
  int h,w,c;
  cin >> h >> w;
  REP(i,h){
    cin >> s[i];
  }
  REP(i,h){
    REP(j,w){
      c = 0;
      if (i>0) {
        if (s[i-1][j]=="#") c++;
      }
      if (i<h) {
        if (s[i+1][j]=="#") c++;
      }
      if (j>0) {
        if (s[i][j-1]=="#") c++;
      }
      if (j<w) {
        if (s[i][j+1]=="#") c++;
      }
      if (!c) {
        cout << "No";
        return 0;
      }
    }
  }
  cout << "Yes";
  return 0;
}