#include <bits/stdc++.h>
using namespace std;
bool vis[55][55];
string s[55];
int n, m;
int dr[] = {0, -1, 0, 1};
int dc[] = {1, 0, -1, 0};
void dfs(int x, int y) {
  vis[x][y] = true;
  for (int i = 0; i < 4; i++) {
    int tx = x + dr[i];
    int ty = y + dc[i];
    if (tx < 0 || ty < 0 || tx >= n || ty >= m) continue;
    if (s[tx][ty] == '.' || vis[tx][ty]) continue;
    dfs(tx, ty);
  }
}
int main() {
  cin >> n >> m;
  for (int i = 0; i < n; i++) {
    cin >> s[i];
  }
  memset(vis, false, sizeof vis);
  int cnt = 2;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (s[i][j] == '#') {
        dfs(i, j);
        cnt--;
        if (!cnt) break;
      }
    }
  }
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (s[i][j] == '#') {
        if (!vis[i][j]) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
