#include <bits/stdc++.h>
using namespace std;
int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> s(h);
  for (auto si : s) cin >> si;
  for (int i = 0; i < h; ++i)
    for (int j = 0; j < w; ++j) {
      if (s[i][j] == '#') {
        bool ok = false;
        for (int k = 0; k < 4; ++k) {
          int ni = i + dy[k];
          int nj = j + dx[k];
          if (ni == -1 || nj == -1 || ni == h || nj == w) continue;
          if (s[ni][nj] == '#') ok = true;
        }
        if (!ok) {
          puts("No");
          return 0;
        }
      }
    }
  puts("Yes");
}
