#include <bits/stdc++.h>
using namespace std;
using ll = long long;
ll MOD = 1000000007;
ll mod = 998244353;
int inf = 1000001000;
ll INF = 1e18 + 5;
int main() {
  int h, w;
  cin >> h >> w;
  string ans = "Yes";
  vector<vector<char>> m(h + 1, vector<char>(w + 1, '.'));
  vector<vector<int>> d = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
  for (int(i) = 0; (i) < (h); (i)++)
    for (int(j) = 0; (j) < (w); (j)++) {
      cin >> m[i + 1][j + 1];
    }
  for (int(i) = 0; (i) < (h); (i)++)
    for (int(j) = 0; (j) < (w); (j)++) {
      if (m[i + 1][j + 1] == '.') continue;
      int cnt = 0, dx, dy;
      for (auto c : d) {
        dx = c[0];
        dy = c[1];
        if (m[i + 1 + dx][j + 1 + dy] == '.') cnt++;
      }
      if (cnt == 4) {
        ans = "No";
      }
    }
  cout << ans << endl;
}
