#include<bits/stdc++.h>
using namespace std;
using ll = long long;
int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};
int main() {
  ios::sync_with_stdio(false), cin.tie(0);
  int h, w; cin >> h >> w;
  int s[100];
  for(int i = 0; i < h; i++) {
    cin >> s[i];
  }
  for(int i = 0; i < h; i++) {
    for(int j = 0; j < w; j++) {
      if(s[i][j] != '#') continue;
      int f = 0;
      for(int d = 0; d < 4; d++) {
        int ni = i + dy[d];
        int nj = j + dx[d];
        if(ni < 0 || h <= ni || nj < 0 || w <= nj) continue;
        if(s[ni][nj] == '#') f = 1;
      }
      if(!f) return (cout << "No" << endl, 0);
    }
  }
  cout << "Yes" << endl;
}
