#include <bits/stdc++.h>
using namespace std;
int n, k, dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0};
char c[100][100];
int main() {
  cin >> n >> k;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < k; j++) cin >> c[i][j];
  for (int i = 0; i < n; i++)
    for (int j = 0; j < k; j++) {
      int f = 0;
      for (int k = 0; k < 4; k++)
        if (c[i + dx[k]][j + dy[k]] == '.') f++;
      if (f == 4) {
        cout << "No" << endl;
        return 0;
      }
    }
  cout << "Yes" << endl;
  return 0;
}
