#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e9 + 7;
const int N = 5e1 + 10;
int dx[] = {0, 0, -1, -1};
int dy[] = {-1, 1, 0, 0};
char str[N][N];
int main() {
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    cin >> str[i] + 1;
  }
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      if (str[i][j] == '.') continue;
      int cnt = 0;
      for (int o = 0; o < 4; o++) {
        cnt += str[i + dx[o]][j + dy[o]] == '#';
      }
      if (cnt == 0) puts("No"), exit(0);
    }
  }
  puts("Yes");
  return 0;
}
