#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  int n, m;
  cin >> n >> m;
  vector<string> board;
  for (int i = 0; i < n; i++) {
    string s;
    cin >> s;
    board.push_back(s);
  }
  for (int i = 0; i < n - 1; i++) {
    for (int j = i + 1; j < n; j++) {
      bool same = true, no_intersect = true;
      for (int k = 0; k < m; k++) {
        if (board[i][k] != board[j][k]) same = false;
        if (board[i][k] == '#' && board[j][k] == '#') no_intersect = false;
      }
      if (!same && !no_intersect) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
}
