#include <bits/stdc++.h>
using namespace std;
const int N = 2000;
int mod = 1000000007;
char rec[55][55];
int main() {
  int n, m;
  while (~scanf("%d%d", &n, &m)) {
    for (int i = 0; i < n; i++) scanf("%s", rec[i]);
    bool f = true;
    for (int i = 0; i < n; i++)
      for (int j = 0; j < m; j++)
        if (rec[i][j] == '#') {
          int dir[4][2] = {1, 0, -1, 0, 0, 1, 0, -1};
          f = false;
          for (int k = 0; k < 4; k++) {
            int x = i + dir[k][0];
            int y = j + dir[k][1];
            if (x < 0 || x >= n || y < 0 || y >= m) continue;
            if (rec[x][y] == '#') {
              f = true;
              break;
            }
          }
        }
    printf("%s\n", f ? "Yes" : "No");
  }
  return 0;
}
